Entropy
by UltimateFandomHub
Summary: [Book 2 of 3: sequel to "The Scientist"] Sans deals with the aftermath of Gaster's disappearance. [Originally by talkingsoup on AO3, crossposted with permission]
1. A Jump to the Left

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 **ENTROPY**

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Note: **This story is not mine**. It is **written by talkingsoup over on AO3** , and I am crossposting their story here **with their permission** to be able to share their wonderful work with the FFN community as well. A link to their account can be found on my profile.

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Chapter 1: A Jump to the Left

 _Don't you know how to greet a new pal?_

* * *

Sans hit the back of the machine and slumped to the floor, dazed. The hatch slammed shut; Sans reached for it, but too slow. There was a clank as the wheel spun and the hatch sealed with a hiss. All at once, the sounds—rending metal, the groan of the Core, distant screaming—died completely. Sans was left with nothing but his own haggard breathing.

He struggled to his feet, trying to reach the handle on the door, but with a high-pitched whine and a burst of light, the machine came online.

"No, _no."_

The hatch couldn't be opened while the machine was active. A failsafe that Sans himself had designed and Dr. Betas had improved on. Sans wished he could go back and punch himself in the teeth.

"D-Dammit…"

He took hold of the handle, but then the machine pitched violently to the side. Sans tumbled into the wall of the machine, somehow managing to keep his grip on the handle. The machine tilted further, and through the window, Sans watched as the catwalk finally gave way.

Everything fell, down toward the darkness. The machine rolled.

Sans caught one last glimpse of Gaster. Long enough to see the look of sorrow in his friend's eyes. Sans slammed his fist against the window and a sound tore from his throat, half scream, half sob.

In the last moment, Gaster summoned a few of his bullets and spelled out two words:

GOODBYE, SANS.

"No…"

The whole world went dark.

In the next instant, a roar filled the machine. Sans clung to the door handle, panicking. Out the window was nothing but black, but the interior of the time machine had started to glow. Particles of white light gathered around him and sparks leapt from the walls to his bones, stinging and burning.

"Oh god, oh _no,_ no no no _nonono—"_

The machine activated, the void splintered, and pain hit Sans like a bolt of electricity. The light engulfed him. He felt himself pulled in all possible directions, but he couldn't move, couldn't even scream.

Was the universe being torn apart, or just Sans?

There was a sensation like unraveling, like tearing, and Sans blacked out.

* * *

Sans came awake on the floor of the machine. He was curled up on his side and wedged into one of the corners. Everything was quiet. Sans blinked slowly, trying to make the world come back into focus. He gave his fingers an experimental flex.

Every last bone in his body ached, but he was alive and whole.

He shifted, gritting his teeth against the pain and trying to push himself to a sitting position. He got about halfway there and ended up just slumping against the wall. The light was gone. It felt like the machine was resting on something solid. Sans peered up at the window. It was dark, but not void dark. He could see what he thought was a tree and the edge of a building roof.

Sans lifted a hand to his eyesockets, trying to massage the ache out of his skull. He needed to get up. Needed to figure out where he was and what had happened. Something was wrong. Missing. It felt as though his mind was full of holes.

He had been in the Core, in a room at the very bottom. The time machine above and pitch darkness below. There had been a fight. Then the doctor had thrown him into the machine and turned it on.

The doctor…

What was his name?

Sans pulled his hand away and stared at his palm. Panic began to well up behind his sternum.

"Doc…"

Why couldn't Sans remember his name?

They had all fallen. Sans in the time machine, the monsters who had followed them. And the doctor. All of them had fallen into the void, and…

Sans dragged himself upright, groaning, breath quickening. If Sans was alive, that meant the machine had worked. It had triggered a Reset. Sans looked out the window again. There was still a world out there. This _had_ to be a Reset, and yet…

His head was pounding. Sans squeezed his eyesockets shut and pressed his hands to his temples. He couldn't think. There was a blank space in his memory, as if something had been cut out.

The doctor. His name. What had been his name?

"Okay, stay calm, stay calm…"

He stumbled to the door and caught the handle. It was more difficult than it should have been. The handle seemed to be skittering left and right, as if Sans was shaking violently. He pushed the door open and stepped out. His feet struck solid earth and Sans pitched forward onto his hands and knees.

Dirt, grass, air. Sans looked around. It was hard to focus on anything with everything vibrating so fast, but he recognized this place. Knew it like the back of his hand.

This was…his home. This was the tiny courtyard behind his and Papyrus's apartment.

Papyrus.

The panic inside him bloomed. His brother, he had to make sure his brother was okay, had to make sure he _still existed…_

He tried to stand, but everything was shaking. _Vibrating._ This wasn't an earthquake. He looked down at his hands. He could feel the earth beneath his fingers, still, solid. But his hands were shaking so fast they had become blurs.

"Papyru—"

Everything seemed to slip sideways. Terror drew a small cry from his mouth. Sans felt himself move without moving. He passed through something dark, then—

The world snapped back into place, only now it was snow beneath Sans's hands.

Sans gasped in surprise and tried to drag himself backward, only to fall into a snow drift. There was snow everywhere. He looked around, trying desperately to get his bearings, trying to understand where he was.

There was a forest in one direction, the stunted evergreens that had subsisted beneath the earth. He was still in the Underground at least. In the other direction were the lights of a town. He squinted. He recognized those buildings. He could even faintly see the neon sign over Grillby's.

This was near Snowdin.

He had traveled from New Home to Snowdin in the blink of an eye.

"Holy shit."

How? This made no sense. Sans hugged his arms, shivering mostly from panic. Skeletons didn't feel cold exactly, but that didn't mean the sensation was very pleasant. He was dressed for Hotland, not the snow.

He got to his feet, bones creaking.

"Okay." He scrubbed at his face. "Okay, think. Calm down and _think."_

Teleportation. That had to be the answer. He had studied some theories about it in the past, had even worked with some potential models on paper. That research had always been overshadowed by work on the time machine and on Reset. It hadn't been important enough to devote real energy to. What's more, it had never actually seemed to be possible, at least not with current understandings of science. Magically, perhaps. Temmies always seemed capable of teleporting, though they kept their secrets.

This was too much all at once. A few minutes ago he had been falling into the Core.

"Just—one thing at once. Deal with this first. Core, the doctor, later."

He had to get back home. Papyrus was the priority right now. He looked toward Snowdin again. It was about a half mile away, and the ferry stopped just north of the town. An hour's trip and he'd be home. This was fine. He could deal with this. Maybe in town he could even find out what day this was. Or…what year.

What year was this? If he had Reset, how far back had he gone?

The panic returned. He could be years in the past. Decades. Papyrus might truly not exist at all.

"Oh god, okay, no, don't think about that. You d-don't know anything yet." He gave a shaky sigh, looking down at himself. His bones were bruised and scuffed, his clothes torn. He looked like he'd been in a fight and had lost badly.

Lost. Sans started laughing, feeling almost hysterical.

"You're a mess, Sans. Look at you. Might want to stop talking to yourself, old buddy. Makes you sound kinda…"

He started to raise his hands to his face and stopped when he saw they were still shaking. There was a faint bluish light weaving through his fingerbones. The vibrating sensation was coming back, rattling his teeth.

"No, wait, stop."

He curled his hands into fists. He whipped his head around, frantic. If he teleported again, there was no telling where he might end up. There had to be something he could do, something he could hold onto…

There was nothing but snow around him.

"Just stop, just—"

The world blurred around him and Sans felt himself wrenched out of time and space. There was that dark place again, then Sans snapped back into existence. There was the popping sound of displaced air.

He sank to his knees, sick and dizzy. Ankle-deep water splashed beneath him, soaking through his shoes. The light was dim and something smelled rather foul. Sans clutched at his head, willing himself to stay conscious.

Once the world came back into focus, Sans looked up. There were massive piles of garbage all around him. This was the dump in Waterfall, where trash from the human world was swept down into the Underground via the rivers. Sans had come here once with Alphys. The place smelled terrible, but it was incredibly useful for gathering materials.

"Great," Sans muttered, voice hoarse. "In with the rest of the trash."

He dragged himself to his feet, swaying but managing to keep his footing. At least he was closer to New Home now. The ferry stopped a few caves away; maybe he could reach it before he teleported again. He chanced a look down at his hands. They were shaking, but it was the normal sort of shaking that came from fear and exhaustion.

This might continue forever, or until Sans vibrated out of time and space entirely.

"Just…have to figure out how to control it. Maybe…if I can just get back to the—"

A voice came from behind him, cutting him off.

"…hello?"

Sans spun, panicking.

"Stay back!"

He summoned his bullets without even thinking about it. The force of his own magic knocked him backward into the water. Bones exploded from the ground in a wave and kept going until the wave impacted the cave wall. Trash and water flew everywhere.

In the midst of it all was a small, floating ghost. The bones passed right through it.

"…oh…"

A split second later, the bones all vanished. Sans sat up in the water, eyesockets wide.

"Oh god, I'm—I'm so sorry I—I didn't mean to—are you okay, I—"

"…oh….I'm sorry…I must have interrupted you…oh no….I'm sorry…"

The ghost started to fade out.

"N-No, wait!" Sans reached out a hand toward him. "Wait, I'm…I'm sorry, I…I don't know how that…"

But the ghost was already gone. Sans dropped his hand to his side. The ghost had seemed unharmed—it was almost impossible to kill a ghost monster—but Sans had _never_ used magic like that before. He had never summoned his bullets without meaning to. If that had been any monster other than a ghost, they would have been dead. How was this possible? His magic was powerful, but not nearly that powerful. That was magic on the same level as G…

He'd almost had it that time.

Sans stared at his hands again. Teleportation, and now increased magic?

"What's…happening to me? What did you do to me, Doc?"

The vibrating sensation started creeping through his bones.

"No, no, not again. No, _please._ Just stop, just h-hold still. _Just hold still."_

He squeezed his eyesockets shut as the vibration intensified. If he could just understand this, if he could just figure out how to hold _still,_ then he might be able to control it.

"Hold still, hold still, hold—"

There was the wrenching sensation again, the feeling of going _sideways._ Sans tried to focus on it this time, the feeling of spacetime bending around him, the actual physicality of it as he traveled.

The world coalesced again and Sans reappeared in another area of Waterfall. Dizziness overtook him and he went down, curling on his side in the dirt.

"Okay," he breathed. "Okay. Just. Stay here for a second."

He lay in the dirt, closing his eyes again as the world wavered and spun. For several long moments, he just breathed. He was so tired. If only he could just fall asleep right here, and then wake up and have it all be just a nightmare.

Eventually, he rolled onto his back and stared up at the cavern ceiling. This was one of the narrower areas of Waterfall, affording him a view of the dim rock above him. This cave was small. There was nothing back here but a single echo flower and a bench, for some reason.

"You're gonna teleport into a wall if you keep this up," he said to the ceiling. "Then you can be a _fossilized_ skeleton. Heh."

"Then you can be a _fossilized_ skeleton. Heh," said the echo flower.

"Ugh."

"Ugh," the flower agreed.

He draped an arm over his eyes. Soon he would teleport again. He had to try and think before that happened. It was hard to think when he was this tired and this scared, but he had to at least try. This was going to kill him if he didn't get the hang of it.

The machine had done this—that had to be the answer. When he and…the others had been testing it, the machine had always generated a lot of excess magic that left any test subject practically humming. It was like the experiment they had done a few years ago, when the Doc had tried to strengthen Sans's soul. The same general principle: pump something full of magic and hope it didn't melt or explode.

That might explain why it had been so painful when the machine had activated. Sans shuddered a little.

The machine filling him with extra magic couldn't be the whole story, though. It explained why his bone bullets had become virtually uncontrollable, certainly. But the teleportation was a bit more complex. Sans remembered that at least two of their living test subjects had vanished into thin air. It wasn't just a matter of magic. The whole purpose of the machine was to unhook from the spacetime continuum and travel somewhere else. Time travel was a form of teleportation, in some senses. You couldn't travel through time unless you could also move through space. Otherwise you would end up time traveling right into the vacuum of space while the planet itself spun away without you.

"At least getting stuck in space would be pretty interesting for a few seconds," he muttered. The echo flower voiced its agreement.

The machine had unhooked itself from spacetime as it was supposed to, but it seemed that it left permanent effects on any subject inside at the time of activation. Or maybe it was specifically because the machine had in fact passed through the void beneath the Core. Sans frowned, trying to remember what that place had been like. He had been focused at the time on the light and magic and pain inside the machine. He remembered a feeling, or a sound maybe, like something had shattered. Like space and time had fractured into pieces. He couldn't remember anything after that.

Somehow, he thought that that part wasn't supposed to happen. The void had been a…he tried to remember. The doctor had explained it to him, but it was so hard to recall. A pathway. A pathway into the past. If such a pathway had broken while Sans was traveling through it, then…

Sans had no idea what that could mean.

The vibrations were starting again. Sans curled into a tight ball.

"Don't panic. Stay calm."

He dug his fingers into the dirt, as if hanging onto the world would keep him in one place.

Think. Focus. Pay attention.

It was a vibration. That had to be significant. Vibration, oscillation, resonance. Frequency, amplitude. Maybe he could think of it like…like tuning a radio or a television. Find the right _frequency_ and—

"Hotland. G-Go to—"

Hotland. Heat, magma, the Core, the lab. Long nights spent working on the machine, on Reset. The terrible coffee in the basement, the good coffee in the chemistry department. The human souls glowing in their sockets on the wall. Falling asleep at his desk, waking to find someone had draped his lab coat over him. The permanent green stain on one wall of the locker room. The doctor, and other people whose names he didn't remember.

The world snapped out, then snapped back in. Sans found himself staring up at another cavern ceiling, this one high enough to be lost in darkness. There was a familiar warm, orange glow all around and the clank of gears nearby.

Hotland.

"Okay. Okay, good."

Sans waited for the dizziness to pass before taking a look around. He froze. He was on a small ledge overlooking a river of magma at least three hundred feet below.

"Hhhh…"

He scooted backward very carefully until he was secure against the cliff wall.

"Yeah, let's. Not teleport into the magma. Let's try to avoid that."

He couldn't see much above the cliff, but on the opposite side of the chasm was an area he recognized. Further along the chasm was a well-used bridge, the one everyone used to get from New Home to the laboratory. The lab had to be on the cliff above him, maybe half a mile away.

"Okay." He drew his knees up to his chest, trying not to look down at the magma. "You got pretty close, so…you're onto something. Right? Like tuning a radio. Heh. Complete with horrible static."

Every successive teleportation was more taxing, though. He had proven that he could control it, if only partially. Now he needed to figure out how to stop it from happening at all.

"Too bad I'm not a radio. Could just switch myself off. Hah." He folded his arms over his knees and let his head rest against them. "God."

The heightened emotions couldn't be helping either. He had been in a state of panic or near-panic each time he had teleported so far. If only he could just calm down.

He thought about resonance again. It wasn't just science. Magic came down to resonance as well. Spells and bullets were your soul resonating at the right frequency with your own magic. Almost all monsters understood that intrinsically, without ever needing to learn how it worked—but not Sans. He had only been able to fully utilize his magic for the past few years. Once the doctor had augmented Sans's soul, it had become easy. Sans could use his magic without thinking about it, like most monsters—but Sans _always_ thought about it. His magic was always purposeful. He _had_ to think about it, because if he didn't, then he would start to take the magic for granted.

Sans had never told anyone, not Papyrus, not the doctor, but ever since the experiment he had kept a certain understanding in the back of his mind. Just because the experiment had worked didn't mean it would work forever. There was always the chance that one day the extra magic would simply overwhelm Sans's weak soul. It could shatter his soul and kill him, or it could simply fade, leaving him as powerless as he had been for most of his life. Sans didn't want to die, and he couldn't even _imagine_ going back to that kind of life. So he was always cautious with the magic. Always purposeful. He always exerted exactly as much effort as was necessary, and never a drop more. Even though the magic had never caused him any undue stress or alarming effects—at least until now—he was still _always_ careful. Most people called it laziness. But when you went through life with 1 HP, having to rely on luck, speed and cleverness just to survive, you learned to be careful.

Or you died.

If he could understand normal monster magic with that kind of mindset, then he could understand this. Resonance. He thought about what it felt like to _not_ use his magic. To be able to do something, but to hold back. To do nothing.

He had always been good at doing nothing.

"Hold still."

He could sense the vibration starting again. Fear curled in his ribcage, but Sans drew in a slow, deep breath.

"It's okay. It'll be okay."

It came on slower this time. The vibration was less violent, less frightening.

"Let's try to aim." He drew in another breath. "Okay. Papyrus. Wait—wait, no."

If he tried to teleport directly to Papyrus, he would scare the daylights out of his brother at best and atomically fuse with him at worst. He was pretty sure that would kill them both. Assuming Papyrus existed at all.

"Nearby. New Home."

He slipped sideways. A moment later, he reappeared—not fused with his brother, or a wall, for that matter. He slumped against something solid, blacking out for a few seconds.

When he opened his eyesockets he found himself in an alleyway, in between two garbage cans.

"Back with the trash," he said, smirking. "Think the universe is trying to tell me something."

He could see the street from here. Across from the alleyway was a convenience store that he recognized. A smile blossomed across his face. He'd done it. He was less than a block from his apartment.

He tried to stand, failed, tried again. Bracing himself against the brick wall, he pulled himself to his feet. Then he started to very slowly make his way to the street.

The street was deserted. Maybe he had gone so far back in time that no one had moved into this part of the city yet. But no, that didn't make sense. That convenience store had been there for only about ten years. And that little clothes shop further down the street, that had opened only a few years ago. That meant that Papyrus must still exist. Right?

Sans told himself not to get his hopes up.

He stumbled off down the street like a drunk. The apartment building was in sight, but the whole world was swimming, and Sans could feel himself starting to vibrate again.

"Come on. Please. Not again. I just want to see him." Sans leaned against a shop window. "Just let me see if he's there."

But fighting it hadn't worked thus far. In fact, it only seemed to make it worse. Sans kept walking and focused. It was like with light blue attacks. You just had to keep still. You just…

Now there was an idea.

Sans stopped and held onto a street light with one hand. The other he laid flat against his chest. He reached for his magic, braced himself, and turned his own soul blue.

 _Ding._

The experience of grabbing his own soul was unsettling and horrifying enough that he almost let go. There was that all-too-familiar heaviness on his soul, only this time he was the one holding it.

A frightened, disgusted sound escaped him. He hated this feeling. It reminded him of…

G…Ga…

Not quite.

"He turned my soul blue a few times." He could remember that, though he couldn't remember why, or what the context had been. "Sounds like he must have been a jerk."

It was unpleasant as hell, but it had worked. He hadn't teleported. The vibrating had stopped. He was still in New Home, just half a block from his apartment. From Papyrus.

Sans released his soul, took a shuddery breath and kept walking.

He made it to the front door without collapsing, and without the vibration coming back. Then he was faced with two flights of stairs. It took another ten minutes just to get to the third floor, clinging to the railing the entire time and almost passing out when he reached the first landing.

The vibration started to come back as he rested at the third floor. He waited. It was far less intense this time. Teleporting seemed to take quite a lot of energy; perhaps his body was simply out of juice. He stood still, breathing, thinking about blue and light blue attacks, thinking about resonance.

It was painfully slow, but the vibration subsided. Sans almost dropped right then and there from relief.

Instead, he dragged himself to the door of his apartment. Moment of truth. He went to dig out his keys, only to remember that his keys were in his bag. Which was still back at the lab. He had left the lab intending to be back in an hour or two—then the doctor had decided it was a great time to destroy the whole world and pilot an unstable machine through a hole in spacetime. Sans hadn't exactly had the opportunity to return to the lab for his stuff.

Of all the stupid things.

He raised a hand and hesitated.

Maybe there was no one living here. Or maybe it was a stranger. If he knocked and a stranger answered, Sans didn't think he would be able to take it.

He knocked.

And waited.

Nothing happened.

"No, please."

He pressed his forehead to the cool wood of the door for a moment, then knocked a second time, louder. He was shaking again, but not from vibrations.

"Please, please, please, don't do this to me, _please—"_

There were footsteps from the other side of the door. Sans's breath caught in his ribs. The door opened.

And there he was. Looking more irritated than Sans had ever seen him and wearing bunny-patterned pajamas.

"ExCUSE me, but do you have ANY idea what time—" Papyrus stopped, and his face went through so many expressions so fast that it would have been comical any other time. He settled eventually on horrified confusion.

"Brother?"

Sans said nothing, staring up at him.

"My _god,_ Sans," Papyrus said, his voice hushed by Papyrus standards. "Do you have any idea how WORRIED I've been? Do you know how late it is? You didn't call! I thought you said you would be home at a NORMAL hour! I tried calling you and you didn't answer!"

Sans blinked stupidly. He reached into his pocket for his phone, noticing too late that his pants were waterlogged. The phone was dripping when he pulled it out of his pocket.

"What in the WORLD happened to you?" Papyrus ushered him inside and closed the door. The apartment looked the same. Exactly the same as when Sans had left this morning.

"You're soaked! You look like you've been rolling in the mud! Oh dear, you didn't track mud all the way up the stairs, did you? The landlord will yell at us again. Sans, what have you been DOING? And why did you knock? Where's your key?"

"P…Papyrus…?"

His voice sounded broken, even to Sans. All of the irritation and confusion on Papyrus's face was immediately replaced with concern. He couched down and took Sans by the shoulders.

"Brother, what happened? You're shaking. Please, Sans, you're scaring me."

"I…s-sorry, bro, I…didn't mean to…wake you."

"Sans, I hardly care about that right now! Just tell me that you are okay."

Sans reached up to cradle Papyrus's face in his hands. Papyrus was the same as Sans had left him. He was real.

The weight of everything hit him all at once and he sagged.

He wrapped his arms around his brother and buried his face against his chest. Papyrus embraced him tightly.

"Sans?"

"I'm sorry," Sans choked out, squeezing his eyesockets shut as he tried to hold back a sob. He wasn't going to cry. Not in front of Papyrus. Papyrus was worried enough as it was. "I'm s-sorry, I didn't… I'm okay. I'm fine. It's fine. Y-You don't need to worry…it's…I just had a long day and I'm s-so glad you're here, I was…scared you were…"

"Oh, Sans…" Papyrus held him tighter. "It's alright now, brother. Whatever it is, it's alright now. I'm here."

Sans clutched at Papyrus's pajamas. A small whimper escaped him. Then a sob. Sans gave up and did something he almost never did.

He let himself break.

He sank to the floor, sobbing into his brother's chest. Papyrus went with him, holding him tight, trembling a little. Sans had to be scaring him, but he couldn't stop.

"Shh, it's alright," Papyrus said, cradling the back of Sans's skull with one hand. "I'm here."


	2. Bad Vibes

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 **ENTROPY**

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Chapter 2: Bad Vibes  


 _So what do you think... of my brother?  
_

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Sans awoke in his own bed.

He couldn't remember how he had gotten here, but he was too groggy to be very concerned. Perhaps he had teleported into bed. He had teleported everywhere else in creation—his own bed was about the most pleasant place he could have ended up. And he wasn't even atomically fused with the mattress. That was a good sign, he figured.

He started piecing together the events of last night. The doctor, whose name he couldn't remember. The Core. The machine…Sans blinked. He had almost forgotten about the machine. Hopefully it was still out back in the courtyard.

He had started teleporting, without being able to control it. Eventually he had dragged himself home. He still wasn't sure what day or even what year this was, but Papyrus was alive and extant, which was the most important thing.

Sans remembered breaking down crying in Papyrus's arms.

He pinched the space between his eyesockets.

"Urgh."

Sans hadn't gone to pieces like that in years. This was going to take some explaining.

He got up, bones still aching. Standing made his back creak as if he was at least thirty years older. Sans put on his slippers and went to the window. The world was still there. Sans could see the machine as well, still perched unassumingly in the courtyard. From here, the machine looked…rather trashed. It occurred to Sans that he hadn't had a chance to check it for damage before he had teleported last night.

He turned away from the window and squinted. Something smelled like it was burning. A fire in the apartment would just be the cherry on top of this shit sundae. Sans headed for his bedroom door and poked his head out.

"Papyrus…?"

"AH! SANS! YOU ARE FINALLY AWAKE!"

Papyrus appeared from kitchen down the hall. He was holding a spatula and grinned when he saw Sans.

"YOU ARE JUST IN TIME FOR BREAKFAST, BROTHER!"

Sans leaned against the doorframe, staring at him. "Break…fast?"

Papyrus had attempted cooking a few times in the past. "Attempted" being the operative word.

"INDEED! I FIGURED YOU COULD USE A GOOD BREAKFAST AFTER LAST NIGHT!"

"Oh." Sans tapped his fingerbones against the door, wondering how long he could put this off. He wasn't sure just how much he could even tell his brother. "Is something burning?"

"NONSENSE!"

"Heh. Don't you mean _nonsans?"_

"UGH. PUNS ALREADY. YOU MUST BE FEELING BETTER. OH, JUST GET OVER HERE BEFORE THEY GET COLD!"

Sans chuckled and trudged down the hallway, keeping one hand on a wall just for security. He felt achy and weak. If nothing else, getting some food in him should help.

The kitchen was only partially filled with smoke. Papyrus had at least opened a window. He was standing over the stove and scooping black disks out of a frying pan onto a plate. Sans gave the disks a dubious look and took a seat at the table.

"So what's on the menu?"

"Pancakes!"

Papyrus set a plate before him. The pancakes had long since ceased to be anything other than charcoal. Sans put on a grin.

"Aww, Paps, you, uh…shouldn't have." He poked one of the blackened disks with a fork. It made a soft _clack._

"A GOOD breakfast means a GOOD start to the day!"

"What time is it?" Sans resisted the urge to also ask what day and year it was. He could discreetly find a calendar later.

"Ten-ish, I think."

"I should probably get to work soon." Sans frowned down at his charcoal. The doctor was gone, but someone at the lab might be able to tell him what happened. He remembered the team working on Reset had been very small, just Sans, the doctor and…someone else. But there were plenty of people at the lab who were at least familiar with the concept. Sans's computer and lab equipment would be able to help, if nothing else.

"Work? You? Ah! That's actually funny! Good one, Sans!"

Chuckling, Papyrus sat down at the table with his own plate of charcoal. He dug in while Sans stared at him.

"…Funny?"

"The Great Papyrus has OUTDONE himself, this time!" Papyrus said around a mouthful of dead pancake. "Anyway, I think it would be best if you stayed in for the day."

"I, uh…" Sans had a very unpleasant theory. "Well, I should at least run by the lab later. Pick up my stuff."

"The 'lab?'" Papyrus gave him a thoughtful look. "Oh! I didn't know you knew any dogs. Are they in the Royal Guard?"

"No…" Any appetite Sans had had was swiftly leaving him. "I mean… _the_ lab. Laboratory?"

Papyrus made a face, as if he had finally realized he was eating charcoal.

"Sans, don't tell me you've been skulking around THAT creepy place. Is that why you were so upset last night?" Papyrus leaned forward. "I heard that place is HAUNTED. Did you meet some ghosts?"

Sans folded his hands under his chin, gaze falling somewhere in the middle distance.

This…this made no sense. Papyrus was acting as if the lab didn't even exist. Or…that it certainly wasn't the lab that Sans was familiar with. What was going on? He had Reset, but the lab and the science division was about a thousand years old. Papyrus and most monsters today had grown up with the lab being as permanent a landmark as Asgore's castle.

How could Papyrus have _forgotten_ such a thing?

"Sans…" Papyrus set down his fork. "Can we talk now? About last night?"

Sans kept his hands folded and refocused his eyes on his brother.

"I haven't seen you that upset since…nyeh." Papyrus didn't finish the thought. "You passed out before you could tell me anything. I want to understand, so that I can help you. You're my brother, Sans. I know you don't like to tell me when something is bothering you, but last night was…frightening."

"Ahh…" Sans dug the heels of his hands into his eyesockets. "I'm sorry, bro. Really. The last thing I want to do is worry you."

"The Great Papyrus is a great brother who worries GREATLY when his brother is crying!"

"Heh." Sans smiled into his hands. "You really are a great brother…"

"And don't ever forget it! Now…are you going to tell me what happened?"

"I—" Sans hesitated. They rarely talked about Sans's work, but Papyrus had always at least known that Sans worked for the science division, and that he was studying human souls. That was about as much as Papyrus had ever really wanted to know, since science bored him. But something had clearly happened to the lab, possibly the entire science division. Papyrus didn't seem to think that Sans even had a job.

Maybe Sans didn't. There was another concern to add to the pile. If Sans was now jobless, he wasn't sure how they were going to pay rent.

"It's…complicated, bro." Sans scrubbed at his face. "I don't…know how to explain it. I had a long…I had a _bad_ day. Some bad stuff happened."

Papyrus frowned very slowly.

"Did someone hurt you?"

Sans flinched and shot a nervous glance at his brother. Papyrus reacted about as well to the idea of someone hurting his brother as Sans did, though Papyrus was a good deal calmer about it. Half the time, Sans thought that Papyrus had convinced himself that _he_ was the older brother, charged with protecting little Sans. It was always a bit amusing, seeing Papyrus march up to some jerk to give them a very stern talking to. Papyrus was a huge softie, but he was very tall and could be quite intimidating without even trying. And everyone knew he was a force to be reckoned with when he was using magic. No one ever bothered Sans when Papyrus was around.

Right now it wasn't amusing. Right now it just reminded him of what the doctor had done, and what he had tried to do. Sans resisted the urge to press a hand to his chest. His soul was still his. No one was going to turn it blue or green or any other color. If the doctor was truly gone, then no one was going to do that now ever again.

"Nah…I don't think so," he said after only a moment's pause. "Do you…remember those earthquakes yesterday?"

Papyrus shook his head. "Were there earthquakes? I didn't notice!"

Maybe they hadn't happened yet, depending on when Sans was. The inability to tell, or even ask Papyrus without sounding crazy, was frustrating to no end.

"I guess they were pretty small," Sans said, voice level. "But, see…this friend of mine was…Paps, you've heard of the Royal Scientist, right?"

Papyrus scoffed. "I might not be as SCIENCY as you, brother, but even I know about that! The position is kind of pointless these days, isn't it? Oh! Sans, have YOU ever thought of becoming the Royal Scientist?"

"M-Me? What?"

"Sure! You would be great at it, Sans! Only…" Papyrus gave him a Look. "You would have to do WORK. I'm sure you would HATE that part."

"I'm—heh—uh. I don't think I get what you mean. Isn't there…already a Royal Scientist?"

"Brother, do you REALLY pay so little attention to the world?" Papyrus shook his head. "King Asgore has been trying to fill the position of Royal Scientist for…hm. I'm not sure HOW LONG it's been, but I'm sure it's a really long time!"

This made even less sense. It was bad enough that something had changed about the lab and the science division. How could there be no Royal Scientist? Ga…

Sans's face scrunched up. It was on the tip of his nonexistent tongue, but it slipped away from him again.

In any case, he, the doctor, had been the Royal Scientist for as long as anyone could remember. Sans knew that much. The doctor had been thousands of years old. He had been the first and only Royal Scientist for all of that time.

Sans massaged his skull, trying and failing not to panic. He didn't understand this. He didn't understand it at all.

With the rising panic came a now-familiar vibrating sensation.

Sans gripped the edge of the table. No, not _now._

"Sans? Are you…alright? You're shaking…"

He took a breath. No, no. He could do this. He just needed to focus. He thought back to last night. Aiming was hard, stopping it was harder, but he had proven that it could be done.

The vibration intensified.

"I—sorry, bro, this—this is going to be scary but—but I'll be okay. It's—th-this is new to me, I'm s-still trying to get—get a handle on—"

"Sans! What is happening?"

Papyrus started to get to his feet.

"N-No—don't go anywhere—d-don't leave—okay? Please. I'll—I'll try to come right ba—"

The world slipped away and a split second later, Sans reappeared. Without a chair beneath him, he went down hard, nearly cracking his tailbone.

"Ow, _dammit."_

He looked around. He was on a roof, still in New Home—the skyline told him that much. He stood slowly, wincing and rubbing his tailbone.

"Good job, Sans," he said around a grimace. "Paps is gonna freak."

He went to the edge of the roof and looked down, trying to spot a familiar landmark. Surprisingly, he hadn't gone all that far. He was two blocks from the apartment building. Judging by what he could see down at street level, he was pretty sure he was on the roof of another set of apartments, this one a bit more upscale than his and Papyrus's.

"Okay…okay, kind of narrowing the focus a bit…that's good…yeah. Yeah, stay positive."

Staying calm was the key. Panicking might send him back to Snowdin, or fling him all the way out to the Ruins.

Sans found a fire escape and started to climb down.

"Hey, Paps, pretty neat vanishing trick, right?" he muttered to himself. "Oh, yeah, I can randomly jump out of space and time thanks to nearly dying last night. Yeah, pretty crazy. This guy I don't remember tried to kill the whole world and wanted to turn me into a science experiment. It was great. Talked him out of it, though. At least I think I did. Can't remember. How was your day?"

He shut himself up when he reached the ground. He was already going to have to walk two blocks in nothing but an undershirt, gym shorts and slippers. If he muttered to himself the whole way then even _he_ was going to start thinking he was crazy.

Fortunately, some of the neighbors were used to Sans wandering around in pajamas, so he got fewer looks than he expected. All the better. He was frustrated enough as it was.

Halfway home, he stopped. In the window of some kind of insurance shop was a digital display, the usual kind that flashed through a cheery greeting message, the current temperature, and the date.

Sans waited till the date came up.

The display showed the date as only a single day after Sans had followed the doctor into the Core.

That couldn't be _possible._ He had Reset, hadn't he? That was what the machine was designed for. How could this be a Reset if he hadn't gone back in time? Had he only gone back a few seconds?

Or…

Was this an entirely new timeline?

No. Sans looked down at his hands. No, that wasn't possible either. If this was a different timeline, he would have run into another Sans by now. He remembered discussing the possibility of jumping timelines with the doctor. Like teleportation, it wasn't feasible with current understandings of science and magic, and the implication had been that even trying could shatter spacetime irreparably. Sans also understood that alternate timelines would contain alternate copies of everyone, Sans included. There was the possibility of a timeline that was somehow missing its designated Sans, but if that were the case here, it wouldn't explain Papyrus's reaction to him.

So this wasn't a new timeline, and he hadn't Reset. It occurred to him, far too late, that similar rules applied to a Reset. He should have run into his past self by now.

What had happened? Sans looked around, ignoring the stares of passersby. It was almost like the timeline had broken and then healed wrong. Like a bone. He and the doctor had fallen into the darkness. Now, according to Papyrus, there was no Royal Scientist at all, and Sans didn't work for the science division. And Sans couldn't even remember the doctor's name, or much about him at all beyond their fight in the Core.

The lab had to have some answers. The doctor had left something there. Something…something important. Sans started walking again, trying to think. Awhile ago, the doctor had created something inside the lab. In…in his office. Something shimmering and strange.

He couldn't remember what it was. Only that it should have stayed constant, regardless of what had happened to the timeline. It should still be there.

First, though, Sans had to get back to Papyrus.

For the second time in as many days, Sans knocked on his own door. Papyrus opened it before Sans could even lower his fist.

He smiled shakily up at his brother, as relieved to see him again as he had been last night.

"Hey, bro. Sorry abo—"

Papyrus leaned down and pulled Sans into a hug. Sans went quiet.

"Sans! Don't SCARE me like that! What happened? Where did you GO?"

Sans patted his back. "H-Hey, big guy, it's okay. I'm okay. I said I'd come back. Let me in, I'll…I'll try to explain."

Papyrus practically hauled Sans inside, not letting go.

"You vanished INTO THIN AIR! You're not usually THAT good at escaping responsibility!"

"Heh." Sans drew back just enough so he could look up into Papyrus's face. "I'm sorry, bro. I didn't mean to startle you. I…can't really control it yet."

"Since when can you just DISAPPEAR like that?"

"Since…last night, I guess." Sans sighed. "I don't know how much I can tell you, Paps. Not…not cause you won't understand. It's…I don't really understand it myself. I don't…know what's happening."

Papyrus leaned his forehead on Sans's shoulder. Sans felt awful. First coming home a wreck and breaking down crying, now vanishing right before his brother's eyes. He had to get this under control. He couldn't keep scaring Papyrus like this.

"Is it going to happen again?" Papyrus asked.

"Probably. Until I get it under control. But I'll always come back, Paps. _Always._ Okay?"

"That's…the most important thing," Papyrus said, lifting his head again. Sans couldn't remember the last time he had seen Papyrus so worried. Papyrus wasn't supposed to be _worried._ He was supposed to be cheerful, happy-go-lucky, boisterous. Upbeat and always positive.

Sans realized all at once that he couldn't tell him. He couldn't tell Papyrus what had happened. Not all of it. Not even most of it.

"This has to do with…what happened to you last night?"

"Yeah, I…" Sans sorted quickly through what he could tell Papyrus that would be the least upsetting while still making sense. It didn't help that Sans barely understood it himself. "Remember I mentioned this friend…this guy I know. He and I were studying something in secret."

"Studying something?" Papyrus frowned. "A 'science' kind of something?"

"Yeah." Sans leaned back against the door. "We tested something last night. And I don't know why, but it affected me."

"So this person _did_ hurt you."

"No," Sans lied. "No, Paps, no one hurt me. It was an accident." He closed his eyesockets. "It doesn't matter now. We both quit the thing we were working on."

"Sounds like quitting was the right thing to do in this case!"

Something sharp and painful nestled within Sans's ribcage.

 _Now is the time for you to quit._

He could almost hear the voice ringing inside his skull. But there was no face or name to go with it. Just impressions. Fear, loss, anguish.

"A…Anyway," Sans went on after a beat. "Do you…remember a few years ago? When I, uh…" Sans paused again. This could be dangerous territory if Papyrus had forgotten the doctor. "I came home and…I could use magic? Do you remember that?"

"I…" Papyrus's frown deepened. He looked like he was struggling with something, some thought that he was trying to pin down. "Yyyyyes? Yes, that's…right. You can…use magic now."

He looked like he was waiting for Sans to confirm it. Like he wasn't certain.

"Yeah. Yeah, that's right."

Strange. Sans would have to think about this later.

"This is kind of like that. It's…heh. It's just a silly new ability, that's all. Just something I need to get used to. It'll be weird for a little while, but…hey, we'll get through it, yeah? It doesn't have to be a bad thing. Right?"

Papyrus's expression was quite firm.

"It isn't painful for you, is it? Or dangerous?"

"What, no. No, not really."

"SANS."

"It's not. I swear."

Papyrus didn't look quite satisfied with that answer, but after a moment he nodded.

"Then I suppose it doesn't have to be a bad thing." He considered Sans, eyes searching his brother's face. Sans tried to look as neutral as he could. "Will you be able to warn me again before it happens?"

"I should be. I can feel it when it's coming on."

"Where do you GO, anyway? If you LEAVE, you must then GO somewhere."

"Heh, it seems like it's…anywhere. I ended up in Snowdin and the garbage dump last night." Sans suddenly grinned. "Hey, you know…once I get this down, I'll never have to walk anywhere again. No more stairs. Heh, dude, it's perfect."

Papyrus stood up and folded his arms, looking mock-disgusted.

"UGH! As if you weren't already a huge LAZYBONES!"

"No more having to take the ferry," Sans said, letting his voice take on a dreamy quality. "No more hopping steam vents. Just, poof. There I am."

"Then you'll be COMPLETELY sedentary! No, I simply won't allow that! I shall have to buy you one of those exercise machines!"

Sans laughed and Papyrus chuckled. There, that was much better. No more worried, confused Papyrus. At least not outwardly. Papyrus could be just as good as Sans at hiding things when he wanted to be.

Sans decided not to think about that. This would pass.

He gave his brother's hand a quick squeeze.

"Hey. We'll be fine, bro, okay? I p…"

He stopped himself. No more promises.

"…I know we will. We're the skeleton bros. Always come out alright, yeah?"

"YEAH!" Papyrus threw up his arms. "More than alright! WE ALWAYS COME OUT ON TOP! DO NOT WORRY, SANS! YOUR AMAZING BROTHER WILL SUPPORT YOU, EVEN WHEN YOU VANISH! TIME AND SPACE WILL NOT COME BETWEEN US, EXCEPT IN A LITERAL SENSE!"

Sans smiled again, and this time it was genuine.

* * *

The rest of the day was quiet. Sans put the search for answers on hold for awhile to spend some quality time with his brother. He slept a few more hours and Papyrus didn't even complain. They watched TV and Sans caught up on what sort of shenanigans Papyrus was getting up to involving the Royal Guard. Apparently there was a new Captain of the Guard, and Papyrus couldn't stop gushing about how cool she was. Neither of them brought up the previous night or its aftermath. Sans was able to put it all out of his mind, just for a little while.

It was nice. Relaxing. Sans hadn't felt this relaxed in a long time.

He teleported just once more during the day, ending up on the other side of New Home. It took him almost an hour to get back home. Sans used the time as an excuse to check on the machine behind their apartment once he got back.

It was right where Sans had left it. Up close, the machine was that much worse for the wear. The hull was cracked several centimeters deep in a few places. The hatch gasket had peeled off and melted, and the entire inside was scorched black. There were exposed wires and piping both inside and out. Sans pressed a few of the buttons on the external control console, but nothing happened. The thing was a wreck. It was a miracle that Sans had survived the trip at all. He traced a finger down one of the worst cracks; any deeper and the hull would have breached. Sans would have met the same fate as the doctor and the others who fell.

He couldn't move the machine like this to hide it, and considering it had been standing out here exposed for several hours, it was very likely that at least someone had seen it. Still—damage control. Couldn't have some kid seeing a cool machine and trying to climb into it. The best Sans could do for now was to cover it with a tarp and move some of the trash bins in front of hit. Hopefully people would just think it was a busted refrigerator.

Once he had found somewhere safe, he could steal a cart and hide the machine. Maybe he would be able to fix it.

Later, though.

Sans went inside, reassured Papyrus that he was okay, and spent the rest of the day not thinking about any of. He tried to just enjoy the calm and quiet.

That night, once he was certain that Papyrus was asleep, Sans left.

It was about an hour's trip to where the laboratory should be. Papyrus was a very light sleeper. If Sans timed it alright, he could get to the lab, take a look around, and be back before Papyrus even woke up. If he wasn't, a sudden teleportation made for a good excuse.

Teleporting would certainly be helpful in this case, but Sans had no idea how to trigger it. He wasn't even sure that it _could_ be triggered. It was possible that controlling the destination was all he could do. Even if he did figure out how to turn it on, the ability might just go haywire again, zipping him all over the Underground until it killed him. Sans wasn't sure he wanted to risk it.

When he arrived at the laboratory and saw it for the first time, he considered changing his mind.

Even at a glance, the whole building was different. It was much smaller. It should have been at least three times the size it was, large enough to accommodate multiple departments. The sign above the door was only one word—Laboratory—and half of the letters had faded.

Sans had never seen a more dilapidated building. The lab had always been old, but it had never _looked_ old. The building maintenance crew had always been excellent at keeping the place clean and modern, remodeling with relative frequency. This lab like it hadn't been used in about a hundred years. Most of the windows were either broken or boarded up. Sans could see that part of the ceiling was caving in. There was a CONDEMNED sign on the door that looked as old and run down as the building itself.

He made a circuit of the whole building. There were two doors with heavy chains on both, and none of the ground floor windows were accessible. Sans came back around to the front door and pulled his lab badge out of his pocket. He grimaced; there was probably no way this was going to work, but he might as well try.

There was a small number pad next to the door with a scanner. Several of the buttons had worn away completely, and there were a few wires sticking out behind the panel. Sans let out a sigh and raised his badge to the scanner.

The open wires sparked and the scanner glitched to life, its screen flashing a few broken pixels and little else. Maybe that was a good sign. Sans typed in the code.

There was a dull clunking sound from the door and it shuddered slightly, rust and dust puffing from the door jamb. The number pad promptly exploded with sparks. Sans stepped back.

"Wow," he muttered, dusting sparks off his coat. "It worked…sort of."

The chain was a problem. It was secured with two padlocks. Sans gave the chain an experimental yank, but nothing happened. He considered his options, rubbing his chin in thought. A few bone bullets would break the chain, but Sans honestly wasn't sure what would happen if he even tried. He hadn't tried to use his magic since that time at the garbage dump.

If only he could just teleport to the other side of the door.

"Stupid idea," he told himself. "Really stupid idea."

Even if he could figure out how to trigger a teleportation, he wasn't nearly good enough at aiming yet. He'd probably end up all the way back in New Home. Or fused with the damn door. So. His options were either possibly blowing up the entire lab with his magic, or possibly teleporting somewhere horrible.

"Nice. I swear, your life didn't used to be this weird, Sans."

The teleporting he at least had a modicum of control over. The magic…he wasn't sure.

Sans closed his eyesockets and took a breath.

"Okay. Let's just…try. Let's see."

He tried to remember what the vibration felt like. It wasn't difficult; he had felt it so many times now that it was as familiar as the sensation of his soul changing color. It was like any other vibration, but much deeper, consuming his entire body and mind. The feeling sank through his bones, all the way to the marrow. Sans remembered. He tried to recapture the feeling.

Nothing happened, but Sans kept concentrating.

"If you can turn a radio off, you can turn it back on. Come on."

That was such an inaccurate metaphor, really. Radio waves had a very long wavelength. The wavelength of this sort of vibration was much, much shorter. A very high frequency. High enough to vibrate though time and space. It would be fascinating to actually study, if it weren't constantly happening to him without his consent.

"I guess it's more like a tuning fork," he said with a shrug. "Sure, okay. Still gotta tune it, yeah? Heh. What do musicians eat their food with? A tuning fork."

There it came, starting from somewhere near his sternum. Sans tried to keep his breathing steady.

"Shit, okay. Okay. Easy now. Into the lab. Into the lab. Into the lab."

Sans kept muttering it under his breath, over and over. He tried to picture the inside of the lab as he remembered it—the white halls, the tile floors, the entryway and the reception desk. Scientists wandering around, talking about the latest experiments or, more often, interesting gossip they'd heard at the water cooler.

The vibration grew stronger, spreading through his bones. It was less violent this time. Less insistent.

He held his breath as he slipped sideways and kept it in when he reappeared. He opened one eyesocket, prepared for the worst.

The orange glow and warmth told him he was still in Hotland, but he was definitely still outdoors. He was also quite a lot higher up than he had been. He opened the other eyesocket and let out his breath, looking around very carefully. This area wasn't familiar. It was very small and partially enclosed, like a sort of alcove. Three rock walls around him and light filtering in from the one opening. Sans leaned toward it.

Ah.

He was directly above the laboratory. It was about a hundred feet below. Sans was in a hole in the ceiling of the cavern.

"Okay," he said, stepping back as far as he could go. "Okay then. I mean. N-Not too bad. At least the…general area is right. Yeah. Bright side. Getting really…really sick of heights, though."

He leaned back against the wall.

"Imagine explaining this one to Papyrus. Heh. Sorry, bro, I got stuck in the ceiling. Can you get me a ladder? Ugh."

He could turn it on now, at least. That much was true. Now he just had to get down.

It took him several minutes to calm down enough to find the vibration again. This time, he reappeared on the roof of the lab.

"Hey, that's better," he said, actually grinning. "Who knows, I might actually get the hang of this. Someday."

Ending up on the roof proved to be a stroke of luck. There was a roof access door, and no one had bothered to chain it up or even lock it. Only a Tsunderplane would be able to get up here, anyway, and what Tsunderplane in their right mind would bother?

Sans paused with his hand on the doorknob. Whatever he found in here was not going to be pleasant. But he had to see it. He had to know what had happened to this timeline, and the lab was the only place that might have any answers. If nothing else, the shining thing that the doctor had left behind had to be here. It _had_ to be. It wasn't the sort of thing that could just disappear, right?

He couldn't remember. Sans pushed open the door.

The stairs had partially rotted through. Sans made his way down them very carefully, hearing the door swing closed behind him. It was pitch black inside. Sans paused on the first landing, gripping a railing and waiting for his eyes to adjust. His ribs felt tight. This wasn't void dark—nothing was—but he couldn't help remembering the Core. The way the darkness had churned inside his mind.

"Get it together, Sans," he scolded, pressing one hand to his chest. "You're a monster. You don't get to be scared of the dark."

After a minute or so, the darkness thinned a little. Just enough for Sans to keep making his way downward. He wished he'd brought a flashlight. It would be just his luck to fall through the floor to his death after everything else that had happened.

The lab had only two floors. The top floor was completely barren. There were a few offices, a small chemistry lab that looked like it had seen at least one fire, a bathroom and a computer lab. Some of the doors were locked, and the offices had been stripped clean. Even the names on the doors had been scratched off. Sans checked every rotting desk and decrepit file cabinet he could, but there was nothing. Most of the computers were entirely gone, or had mice living inside busted monitors. Any important information from this place had either been removed or destroyed. About an inch of dust coated everything.

Worst of all, Sans barely recognized a thing. Sure, the chemistry department had been on the second floor, but it had been much larger. Two huge labs, decontamination showers, a giant storage room, several refrigeration units, the works. Sans could remember the weird smells and constant chatter from the chemistry nerds. Chemists were an entertaining lot.

Sans wished he could remember any of their names or faces.

Even the offices were unfamiliar. Sans didn't think he had ever had an office, but he had had a desk…somewhere. The physics department was supposed to be on the third floor, but there _was_ no third floor. In the last few years, though, he'd been keeping most of his stuff in the basement. That's where they had been working on Reset.

He made his way to the ground floor. Down here had been engineering, magical engineering and the medical wing. There was no way a building this size could hold three entire departments on one floor, though. There didn't seem to be any rhyme or reason to what the timeline had kept and what had vanished. Why keep chemistry but not physics? If there was a pattern here, Sans couldn't see it.

At least things were more familiar on the ground floor. The entryway was virtually the same. There was still a computer at the reception desk, but it was broken beyond all repair. There was graffiti on the walls. The magical engineering department had disappeared, but as his footsteps echoed down the dark, empty hallways, he couldn't help a sense of déjà vu. He recognized just enough for the place to be uncanny. Here was where one of the scientists from Snowdin had first told him about a nice diner called Grillby's. There was where he had once witnessed two lab techs daring each other to drop raw sodium in the toilets. Here, in this hallway, in this spot, Sans had once handed a blue human soul to the doctor.

 _Please don't make me do something like that again._

He could almost hear himself saying it. It felt like centuries ago. Sans came to a stop, covering his mouth with a hand.

The humans. He had forgotten. Sans closed his eyesockets. Right. Waterfall. The child with the frilly dress. They'd been scared and alone and Sans had killed them.

For science. For _him._ He had convinced Sans that it was worth it. That _Reset_ was worth it. He had tried to tell Sans, over and over, that it had been the right thing to do. And Sans had tried to believe it.

"And this is what we got," he said to the empty lab. "Dead kids, dead scientists and a busted-up timeline."

The blue one hadn't been the last. There was another one later. Sans braced himself against the wall as he remembered. The boy. The one with the green soul. Sans had turned him over to the Royal Guard, all but assuring his death.

"Dammit."

Sans inhaled and moved on, shoving his hands in his pockets, shoulders hunched. He couldn't dwell on that now. He had come here for a reason.

The doctor's office should be further down this hallway. That was where the important thing was hidden. The shining thing. And beyond that should be the elevator to the basement.

Sans felt his ribs start to clench as he spotted the door to the office. It still existed, at least. His pace slowed as he approached the door. He almost felt that if he were to open the door, the doctor would be there, waiting on the other side as if nothing had happened. As if he was still alive.

Sans spotted the name placard next to the door and stopped. The name had almost completely worn away, which was normal considering the state of the rest of the building. What was strange was the way the name had been written. It didn't look like normal letters. Sans could only make out one—a hand sign with one finger pointing up.

"G," he said aloud and then frowned. How did he know that? It was just a hand sign. Did it really correspond to an actual letter?

He reached up and tried to brush away some of the dust from the placard, but it was no use. The other letters, if they really were letters, were all too faded. There was a deep crack right down the middle of the name.

"Hands." He traced the faded impressions of the symbols with a finger. "He…spoke with hands."

He could almost remember. It had been like an entire language. A language that Sans understood. If Sans could figure out what the rest of the letters had looked like, he had a feeling the language would come back to him. He couldn't remember it right now, but it was there in his mind. Whatever had cut out his memories of the doctor hadn't excised this one entirely.

He added that to the list of things to think about later. Time was running out; Papyrus would be awake before too much longer. Sans had to try and find the shining thing and the basement before that.

His hand went to the doorknob. He half-expected the office to be locked, but the knob turned. A shiver ran through Sans as he pushed open the door.

The office looked almost normal. There was a large wooden desk that was covered in cracks and dents, as if something had struck it repeatedly. The office chair was overturned and missing its wheels. There was a sturdy, locked file cabinet in the corner, two broken lamps and a pot that was filled with dirt and dead leaves. In the opposite corner was a bookshelf, one of its shelves broken, and containing only a handful of intact books. There was an old, torn poster of the periodic table on one wall, but it was the only personal touch in the room. No picture frames, no awards or trophies, not even a framed degree on the wall.

It could have been a normal office if not for the oppressive atmosphere that rolled over Sans like a cold wave. The feeling was strange, like when the pressure in a room changes, or when you hear a subaudible sound like a distant whine or hum. Sans shivered again and his head started to swim. Something was very wrong with this place, moreso than the eerie vibe of the rest of the laboratory.

He chanced a step over the threshold. The pressure seemed to increase infinitesimally. Almost like he was being pulled underwater.

"Get a grip, Sans," he whispered. He didn't want to speak too loud. It felt as though he was disturbing something that shouldn't be disturbed.

His gaze settled on the spot on the floor where the shining thing should have been. It wasn't there. There was a small scorch mark on the carpet, but that was all.

This made no sense. The thing should have been here. If he could just remember what it was, he would know _why,_ but he knew that something like that couldn't have simply been moved or stolen.

Sans crouched down over the scorch mark, trying to ignore the pressure in the room.

"It's more than that," he said, very carefully tapping the mark with a finger. "This thing. It made it so…so he could come back. He… _should_ have come back, but…he hasn't."

It had been like an insurance policy. The doctor had explained it to Sans and…and to the other one…but Sans couldn't remember. The point was, if anything were to happen to the doctor, this _thing_ should have allowed him to return. To…Reset, in a sense. The thing should have saved him.

Sans almost fell over.

"Save." He gripped his cheekbones. "He made a _Save."_

Like pinning down a piece of spacetime. That was how the doctor had described it. A point to which he could Reset should anything happen. It had glowed gold. Looking at it for too long had given Sans a sort of headache. Just like this room. Eerie. Wrong.

"Alright," Sans said, standing again. He started to pace. "Alright, alright. So he made a Save—never mind that that shouldn't even be possible—he made a Save and now it's _gone._ Also impossible."

The oppressive atmosphere in the room was too much. Sans went back out into the hallway and continued pacing there. Sometime later he could come back and check the file cabinet to see if anything was there, but not now. He couldn't go back in there. And right now he needed to think about this. He looked at the desk through the doorway, frown deepening.

"You made a Save and it couldn't even save you. You're dead, Doc. All of it was for nothing."

He pulled the door closed, unable to keep looking at the office. He gritted his teeth and rested his forehead against the door.

"Why can't I just _remember?"_

Maybe Sans was the crazy one. Maybe this timeline was normal; maybe the doctor had simply died years ago. No Save, no Reset, no falling into the Core. Sans couldn't even remember most of it. Years working with the doctor, years working _here,_ and yet all he had were fragments.

He felt like he was losing his mind.

He tapped his skull against the door again.

"Just…keep it together, Sans. Keep it together."

Sans stayed like that for a few minutes until his breathing settled and the desire to smash his head through the door had passed.

Crazy or not, he had to figure this out. He wasn't allowed to lose his mind. He had a brother to look after. A brother who would be waking up and wondering where Sans had gone if Sans didn't leave soon.

One more thing. Sans continued off down the hallway toward where the elevator should have been. A few steps was all he needed. The hall came to an end just ahead. No elevator. No sign that there had ever been an elevator. Not even a flight of stairs indicating that there might have been a basement at all.

Sans wondered what that meant for the human souls. They had been keeping them in the basement whenever the rest of the science division or Asgore didn't need them. Maybe they had simply vanished along with most of the other things Sans could barely remember.

This was exhausting. Sans had seen enough. He would come back later and give the place a more thorough look. Go through all the filing cabinets, dig around in the locker room. Maybe he could get a hold of some blueprints for this current version of the building, find out if there was a basement or anything else he had missed.

For now, he was done. He couldn't take this anymore.

He leaned against the wall at the end of the hallway and closed his eyesockets. It took him longer to find the vibration this time, but there it was, almost like it had been waiting for him.

"Home," he said.

The world slipped. Sans opened his eyesockets.

He was on a roof just two buildings away from the apartment. Sans smiled a little despite himself. Then he climbed down and made his way home.

Papyrus never noticed a thing.


	3. What Stays

.

 **ENTROPY**

* * *

Chapter 3: What Stays  


 _Hey, I know the feeling, buddo._

* * *

Sans got busy over the course of the next week. There was a lot to be done. Papyrus wasn't very keen to let Sans leave the house, but Sans assured him that he would be careful. His brother had work of his own to do, so it wasn't like he could babysit Sans. Papyrus eventually folded. Sans hadn't even needed to use the big brother card.

Whenever Papyrus wasn't around, Sans was working. He started keeping records, detailing everything he remembered from before the events at the Core and everything he had discovered afterward. He made charts mapping all the changes between the two so that he could have a visual representation of the diverging timelines. He spent most of his time in the library, catching up on current events and recent history. New Home kept a very extensive and thorough archive. It took quite a lot of digging, sometimes literally, but Sans managed to get his hands on records of the laboratory, including blueprints.

The blueprints were fascinating. A lot of the floor plans, at least in the smaller rooms, were identical to what Sans remembered of the old lab. They also indicated that there might actually be a basement after all. The plans mentioned a basement, but there were no floor plans or drawings at all—just contractual and construction records. There even seemed to be an elevator shaft, hidden behind the wall, exactly where Sans remembered it being. Upon visiting the laboratory a second time, Sans drew an outline of it in chalk. The elevator itself was gone, but the shaft was still there.

Sans tried to teleport down into the basement, and instead ended up under a mound of trash in the Waterfall dump. He decided not to try again until he had better control.

Every spare second he had, he was practicing. Calling on the vibration had gotten quite simple, but aiming it and stopping it from happening randomly were still a problem. Still, he was making progress, day by day. Even when it came on suddenly, it wasn't nearly as unpleasant and startling as it had been before. Sans had even managed to keep from teleporting away or back while Papyrus was looking.

It might be months before Sans could teleport to wherever he wanted, whenever he wanted, but the mere fact that he could control it at all was incredibly heartening.

Aside from teleportation and record keeping, there was plenty else to do. Piecing together the major differences between this current timeline and the old one was relatively simple, but the problem was doing it without Papyrus or anyone else finding out. It wasn't like Sans could go around asking questions about things that should have been common knowledge. By the end of the week, after hours sorting through books, archival records and newspapers, Sans thought he understood most of it.

The story went thus:

Once, either a long time ago or not, there had been a Royal Scientist. No one remembered his name or who he was, and Sans could not find a single record on him, save for the fact that the Royal Scientist had built the Core. Sans had explored the Core a little bit, and it had looked the same as ever—though he had avoided going in too deep.

There had never been a science division, but the Royal Scientist had had a small team that operated out of the old lab. Sans did manage to find a record on the team, but a lot of the names on it had been redacted. One day, there had been some kind of accident, and the Royal Scientist and several of the team members had disappeared. There had not been a Royal Scientist since, though Asgore was constantly trying to fill the position. The laboratory had been abandoned.

Not too much else had changed in the Underground, except for little things. The four human souls had survived the divergence, or breakage, or whatever had really happened to this timeline. The souls had been in the basement lab at the time, but now they were housed in Asgore's castle. How they had gotten there, and how they had survived at all, Sans wasn't too sure. He had an idea, though. Determination was a powerful thing.

Sans studied the names on the list. Quite a lot of them were familiar, and the more Sans thought about it, the more he remembered. This monster had worked in engineering, that monster had worked in robotics, and so on. He started to remember their faces, their personalities. This was only a fraction of the staff at the lab—there had been hundreds of scientists and other staff in the science division—but it was a place to start. Maybe if he tracked down the ones on this short list, he would be able to find others. And maybe someone among them all would remember something.

He started going down the list. Some of the monsters on it were dead. The rest had either moved on from science or had started working at other places scattered through the Underground. Some of them worked in the Core now, and still others were professors at the university. Sans tracked down as many as he could over the next several weeks, making up legitimate excuses to talk to them. A research project, a survey, a genuine interest in their work. Whatever scenario made the most sense for each monster.

Some of them didn't want to speak to him at all, stating outright that they had no interest in talking about their years working with the Royal Scientist or even remembering him. The ones who did talk, however, all had very similar stories.

"No, never met him," said a Woshua who had retired to Waterfall. "Was a busy monster. Busy, busy. No time for Woshua. Cleaned up a chemistry experiment one day. _Filth._ Couldn't help it. So, they fired me."

"Oh, that was awhile ago, wasn't it?" said a dog monster who had become a mechanic in Snowdin. "Wasn't it? It was good working there, but I never liked Hotland. The heat mats your fur all the time! No, sorry, I can't tell you anything about him. Was it a him? I don't remember. It was awhile ago, wasn't it?"

"Sure, the Royal Scientist, sure," said a rock monster who worked for a small chemical company in New Home. "Those were my halcyon days, that's for sure. Bright minds coming together for the betterment of monsterkind. Whatever happened to that? It all just fell apart one day. Odd. I try not to think too hard about it. I'm sure I must have met him at least once, right?"

"He couldn't have been _that_ important if I just forgot about him," said an Astigmatism who had a private optometry practice in New Home. "No time for medical advancements there! Nope, craft these lenses, we need more microscopes! _Microscopes_. Make us some nice prisms, Stig! Bah! Always picking on me! So I quit. Now I get to pick on everyone else! Heh. Say, I know you don't have eyes, but have you considered getting glasses?"

"Have we met?" said a snake monster who worked in the Core. "You seem familiar."

Sans stared at the snake monster for a moment. She had worked in engineering. He had once bought this monster a celebratory drink at Grillby's after she had announced that her wife was pregnant. Sometime later she had shown him the baby pictures.

"I get around a lot," Sans said. "Maybe we met once?"

"Life is funny like that, isn't it?" She tilted her head, studying Sans before she continued. "As for your question, no, I don't remember him. I remember how great that engineering team was—I've lost contact with most of them. But I don't remember _him._ I don't think anyone does."

She gave Sans a pointed look.

"Maybe you shouldn't dig too deeply into this."

Sans thanked her and moved on.

From the original list, Sans was able to get more names, mostly by simply asking monsters about anyone else they knew in the scientific community, or anyone they knew from the university who had studied any of the sciences. Before the timeline broke, only the absolute best had worked for the science division, but any scientist worth his sodium chloride had certainly aspired to work there. The laboratory had never been the _only_ laboratory in the Underground, but it had certainly been the biggest and most well-known. On the growing list of names, at least some of them had to have worked for the old science division, but not the new one. Scientists who would have been in the physics or magical engineering department. The departments and the science division had disappeared, but the actual monsters who had staffed them couldn't have. They had to still exist—Sans just had to find them.

As with the original list, compiling the new list triggered more memories. He could remember these monsters, especially his fellow physicists. When he wasn't working with the doctor, he was working with them. He knew their names, had met their families, had hung out with them outside of work. They'd been his friends, not just his coworkers.

One by one, he tracked them down. And this was where Sans began to notice the more subtle deviations from the original timeline.

Sans found twelve monsters from the physics department in total. Of the twelve, five were not even remotely the monsters that he remembered. They looked the same and had the same names, but that was it. They had never pursued science at all. All five were living perfectly normal lives in the Underground, some with families Sans didn't recognize.

When Sans thought about it, it made a horrible sort of sense. He remembered talking with these five. He remembered them telling him that the Royal Scientist had been their inspiration. The doctor and his impressive body of work had been the reason they had gotten into science in the first place.

Without the doctor, they had pursued other interests and had ended up in vastly different lives.

Not a single one of them knew Sans, but as he talked to each one, he saw a strange look in their eyes. Almost recognition. Like déjà vu.

The other seven had pursued science and had ended up in physics, but had still come out different. Three of them worked at a small lab in Hotland, where they claimed they had been trying for years to get the funding to build a particle accelerator. Two of them taught at the university. One worked at the Core and had done so all his life. And one, the old head of the physics department, who the Royal Scientist had cherry-picked during his internship, had simply dropped out of school and now wrote books from his home in Waterfall.

And none of them knew Sans. He had worked directly with these people, had shared math jokes with them, had argued theories with them, had been to their homes for dinner, had attended their weddings…and none of them remembered him. Save for that vague look of recognition in their eyes.

By the time he had gotten through all twelve, Sans simply couldn't handle that look anymore. He compiled everything he could into his notes and gave up. No one remembered the doctor, and no one remembered Sans, either.

It was an odd feeling, to be so abruptly short on friends.

All the other names turned out to be more of the same or just dead ends. Eventually, there was only one last person that might know anything, and Sans wasn't holding out too much hope. Alphys had only ever been an intern, and had only met the doctor once or twice. What's more, aside from the doctor, she was connected to one other person who had fallen into the Core—her father. Sans couldn't remember his name, or much of anything about him, but he knew that Alphys's father had been one of his close friends. He had been the third part of the trio that included Sans and the doctor. The three of them had been working on Reset together, and even though Sans couldn't remember his face, Sans knew with every bone in his body that he had fallen into the Core with the rest of them. Entering that darkness at the bottom of the Core meant that you were excised from the timeline.

There was a good chance that Alphys wouldn't even remember her father, just like no one remembered the doctor.

Tracking down Alphys took a bit of work. Sans didn't exactly have the name of her father to work from, and though he and Alphys had hung out once or twice, he had never been to her home. He checked the university, where she should be finishing her doctorate, assuming the new Alphys had gotten into science at all.

Fortunately, the university had records on her, not all of them technically available to the public. Alphys was indeed still pursuing her engineering doctorate, though when he went looking for her, he found that she was currently taking a month off for "personal reasons." From there he had to find her apartment, not far from the campus.

He tried calling a few times, but she never picked up. The first time he tried knocking, there was no answer. He came back the next day and tried again. This time she answered.

She looked the same as he remembered—a yellow lizard monster not much taller than he was, with head spines and a bit of a bucktooth. She was wearing pajama bottoms and an oversized T-shirt with a cartoon character on it.

"H-Hello?"

Before Sans could say anything, Alphys's eyes widened.

"Oh, I…I know you, don't I?" She frowned. "Sorry, s-sorry, ugh, this is so awkward, I just, I'm totally spacing on your name…"

He blinked at her. "It's…Sans."

"Sans. Yeah." Her frown deepened.

There was a silence, during which Alphys stared at Sans.

"So, uh," she said, nervously tapping her claws on the door. "What are you…I-I mean, can I help you with something?"

Sans scratched the back of his skull, wondering what this meant. It was surprising enough that Alphys remembered him at all. He had been prepared for her to not recognize him and to simply launch into his spiel.

"Sorry, I hope I'm not bothering you. I was wondering if we could talk? I'm, uh, conducting research on the scientific community in the Underground. I was hoping I could get your insight on…a few things."

"Oh." Alphys was looking more confused by the second. Sans was getting very familiar with that expression. It was the expression of someone trying to piece together what they knew, what they thought they knew, and what they had forgotten.

"I'm just a student, though," she said, fidgeting. "I mean, I'll be graduating soon, but…"

She stopped and looked Sans in the eye.

"There's something else, right? I…can't remember how I know you. But we _do_ know each other. Right?"

This was very different from the previous times. Even the snake monster had remembered Sans less than this.

"We do. Sort of…"

Sans hesitated, trying not to get his hopes up. Maybe, though…maybe this was worth a bit of a risk.

"I…I worked with your father."

Alphys's eyes widened.

"But that's impossible."

Sans sighed. "Yeah, I—"

She reached out and grabbed Sans's wrist before he could finish.

"We—we should talk. Come in."

She let go and opened the door wider, stepping aside to allow him. Sans paused, looking between Alphys and the open door. Then he went inside. Something was happening here. Something interesting. This might be the first real lead he had.

Alphys's apartment was modestly sized. There were clothes and papers strewn about all over, as well as the occasional action figure.

"S-Sorry, it's a mess, I know," Alphys said, shifting things out of the way with her feet as she led Sans down the hall. "I-I didn't think I'd have company. I went on leave and no one's…really come to visit me? God, I'm wearing PJs aren't I? Ugh. I'm sorry."

"Hey, it's fine." It really wasn't that bad. No worse than his own bedroom. "I'm sorry for just showing up. I tried calling but…"

"Yeah. Yeah, I, I turned off my phone. It's. It's been weird. Anyway, um." She stopped in the kitchenette and indicated a small table with mismatched chairs. "You can…sit if you want? Do you want, um, tea? Or—actually I'm out of tea. D-Do you want soda?"

"Sure, yeah." Sans took a seat. He had a feeling he would want to be sitting for this conversation. Nervous energy was threading through his bones, and he was trying hard not to seem desperate. This could be nothing. Another dead end. It had been a month now, or close to a month, with no solid answers.

Sans felt the first hints of a vibration shuddering near his sternum. He tamped down on it. No way was he going to teleport until he knew for sure. He stilled, folding his hands on the table.

Alphys poured two glasses full with fizzing yellow liquid and set one in front of Sans. Then she grabbed a thick folder from the counter and sat down in the other chair, across from Sans. She laid the folder very carefully on the table.

"So you…you worked with my dad."

"Yeah," said Sans, taking hold of the glass of soda but not drinking it. "At least I…think so."

"You _think_ so?" Alphys folded her hands under her chin and peered at Sans. He could tell she was trying to look confident and skeptical, but he could see her trembling.

"My dad disappeared a long time ago. So…so unless you're way older than you look…" She trailed off, waiting for him.

He smiled faintly. "I always thought skeletons looked kind of ageless."

"It's your voice, I guess. I think. I…"

She was trembling in earnest now and finally unfolded her hands, wiped them on her pajama bottoms and then grabbed the folder. She didn't open it, instead just staring at the manila cover. There was unsteadiness in her every movement.

"How do _I know you?"_

Alphys sounded as desperate as Sans felt.

"I don't know," he admitted. "You interned at the place I was working. We met a couple times. But…"

"But that's not _right._ I interned at a robotics company in Hotland. That was last semester. I remember it all really clearly. _Really_ clearly. N…No one there really liked me. I-I kept making mistakes, and… You weren't there. I would remember you, but I don't. You were never _there."_

"I…"

He didn't know what to say. This was a lead, an incredible one, but…he was _scaring_ her. She was shaking outright now. This was like with Papyrus all over again. Maybe this was just how it was going to be. Whatever had happened to the timeline had affected everyone, the entire Underground, maybe the entire world. But it hadn't affected Sans. Not in the same way. It was like…like the entire world had broken around him, but Sans had only cracked.

He was starting to feel cracked more and more lately.

Could he really do this to people? Try and force them to remember things they shouldn't? He thought about that look of vague recognition, that look of confusion, the snake monster's warning not to dig too deeply.

"I'm sorry." He started to get to his feet. "I shouldn't have come here. I didn't—I didn't mean to upset you. I'll go. I won't contact you again, okay? Just. Forget any of this ever happened, yeah?"

"No. No, wait!"

Alphys scrambled to her feet before Sans could even leave the kitchenette. She reached a hand toward him, clutching the folder to her chest with the other like it was a security blanket.

"D-Don't say that. F…Forgetting…is the problem, isn't it? Isn't it?"

He stared at her, one hand on the kitchenette doorframe. Alphys flipped open the folder and started thumbing through it.

"I-I…I've been keeping notes. I d-didn't want to bring this up, I thought people would think I was crazy, I thought _you'd_ think I was crazy. I _feel_ crazy! But then you showed up and said you worked with my _dad._ I don't know what's going on…"

"Okay." Sans held up both hands, speaking as gently as he could. "Okay, just slow down. Just. Start from the beginning, alright?"

Hope was budding in his chest and he hated it.

"I won't think you're crazy. Just tell me what it is."

"I don't know what it is," Alphys said, dragging one hand down her face. She sounded utterly exhausted. "Okay…listen. So…I'm just a student, right? I'm finishing my Ph.D. Everything was normal, I was just, just taking classes and working on my dissertation. And then…a month ago…something…something happened."

Sans hissed in a breath through his teeth. Very slowly, he went back to the table and sat down.

"Go on."

Alphys sat as well, setting the open folder in front of her. Sans sneaked a glance at it but couldn't read the handwriting.

"I don't really _know_ what it was. Everything was normal and then one night, I'm watching this new anime I found at the dump and in the middle of it…I get this…feeling. It's…I don't know. It was the worst thing I'd ever felt. Not, like, pain or anything. It was like _loss._ Like this…intense feeling of loss… Only I didn't know what I'd lost. I go into classes the next day and the feeling is still there. I-I-I'm used to…feelings kind of like that…b-but I…usually it's triggered by something, and this _wasn't._ I-It was so bad I had to go on leave. I've been away for a month."

Sans nodded.

"I went by the university before I came here. They mentioned that. This…this started a month ago?"

"Yeah. I kind of h-holed up here at home. I thought maybe I just needed a break? Maybe it was school stress? But I started having…dreams."

"Dreams?"

"About my dad. They were like memories of things that had…never happened. He disappeared a long time ago. But every time I had one of those dreams, I'd get that feeling again."

Alphys groaned and abruptly dropped her head into her hands.

"I don't know why I'm telling you any of this. I don't even really know you."

"Please. Go on."

She was quiet for awhile, eyes closed, head in her hands. Slowly, she lifted her head slightly and opened her eyes again.

"I started realizing…how little I remembered him. Every time I thought of my dad my memories were hazy. He was there…I could remember him. But I realized…I had so few pictures of him. He wrote a book once, but I couldn't find it anywhere. He wrote a bunch of stuff and built machines but I couldn't…it…it was like s-something had happened. To my memories of him. At first I thought it was just because he had disappeared so long ago, but…it kept happening. So I started keeping notes. About the dreams, about what I remembered, about him in general. And…and things…d-didn't make sense. I thought I was going crazy. It wasn't just my dad. There were all these l-little things that didn't make sense. Th-That I remembered wrong. I felt like I should just ignore it and…and just think of it as being confused. I mean…m-maybe I'd had a nervous breakdown or something? And that was why everything was s-so weird? But then I called up my aunt and my uncle…they're his brother and sister. And I tried talking to them about him but…but everything they said was so vague and weird. Like…they remembered him, but like their memories were just as hazy as mine. Only they didn't question it. I-I don't think he really got along with them. It felt like…like either I was going crazy or the whole world was. Then. Then the other day, I remembered something. My dad gave me this box one time. He told me…something important, but I can't remember what it was. I'd kept the box locked all this time but I finally opened it and…"

Alphys fell silent again and drank her entire glass of soda in one go. She burped quietly under her breath, then flipped to the back of the folder. There was a thin, spiral-bound notebook there as well as a couple photos. She picked up the photos before Sans could get a good look at them and held them in front of her, staring at them as if they made absolutely no sense.

Sans's gaze fell on the notebook. On the front was a single word.

RESET.

He covered his mouth with a hand.

"Alphys—"

"Nothing made sense." Her voice was hushed, shaking. "And then you showed up and I _knew_ you, and it made even _less_ sense."

She set down the photos in front of him.

"Do you recognize these?"

There were three of them. The first was of a middle-aged lizard monster with green scales. He was wearing glasses and a lab coat and was smiling into the camera with just a hint of nervousness. It looked like a professional headshot, the kind you'd attach to a resume.

The second photo was of the same lizard monster. It was a candid shot of the monster looking up in mild surprise at the camera, as if the cameraperson had caught him off guard. He was seated at a workbench, looking tired as he pieced together some complex bit of machinery. There were blueprints unrolled next to him, three corners held down with coffee cups. Sans recognized the blueprints. They were the original design for the time machine currently hidden in Sans's backyard.

He recognized the photograph itself as well. It was suddenly so clear. Late at night, hard at work in the basement. Sans had been texting Papyrus to let him know he would be home late, and he had looked over at…at…at him, the lizard monster, where he had been sitting at his workbench. Sans remembered thinking he looked so funny. The monster had this habit of scrunching up his brow when he was concentrating. On a whim, Sans had raised his phone and snapped a picture. Only the monster had seen him move and had looked up just in time. The monster had laughed and scolded Sans, reminding him they weren't supposed to take pictures of any of their work in the basement, and that Sans would be dead meat if _he_ caught them, and Sans had pointed out that he would be dead _bones,_ and they had both laughed some more.

And then there was the third photo. Three monsters, staring into the camera and grinning. Sans. The lizard monster next to him. And behind them, his hands on their shoulders, a third monster that Sans didn't recognize.

They looked happy.

Sans pressed both hands to his skull. A sharp pain was spreading through his cranium the longer he looked at the third photo.

"How—how do you have these?"

"I-I don't know," Alphys said, sounding more uncertain than she had yet. "I just found them. They were in the box, along with the notebook. That's…you, isn't it? You really did work with him. But these must be from _ages_ ago."

Sans winced as the pain in his skull intensified. He looked away, eyelights flicking back to Alphys. The headache vanished almost instantly.

"What was his name? Please, I—I can't remember."

She cocked her head. "His name was…" She paused and frowned. "It's…hard. I don't know why. His name was Betas."

There was the sensation of something clicking into place. Of one of the holes in Sans's mind being filled.

"Dr. Betas." Sans breathed deep. "Alphys, I…you're the only other person who…remembers _anything._ I don't…get it. Why you? And…how are there _pictures?_ I've looked everywhere. I've been digging all over and I could never find anything. Not on him— _Dr. Betas._ That was his name. God. That was his name."

"Sans, what _happened?_ I don't understand. I—I can't figure this out. Even the notebook, it's, it's in this weird _code…"_

She flipped open a random page and showed it to him. The entire page was filled with strange symbols. Hands, mostly.

"I know this writing…" Sans said, his eyelights shrinking as he gingerly took hold of the notebook. He flipped through a few more pages. All of it was written in those symbols, except for a few mathematical equations, graphs and figures.

"I can't believe this…"

"And those pictures. I mean, these two are normal, but _this_ one…" Alphys tapped the third picture. Sans chanced another look at it, but even a glance made him feel like the world was lurching sideways. He almost teleported right then and there but clamped down on it before he could.

"It's weird. It's like…like looking at one of those optical illusion gifs. Or like those models that are supposed to represent four-dimensional space but they just look _weird._ Sans, please, you've g-gotta tell me. I need to know what's going on."

Sans set down the notebook and cradled his head in his hands.

"Give me a sec. Just…I need a second."

He felt like he was stuck in the middle of a teleport, in that place _between,_ where things were dark and nothing made sense. He needed to breathe. He was here. In Alphys's apartment. In New Home. In the Underground. He was here.

Slowly he lifted his head.

"I…don't know how much you'll believe me. It doesn't make much sense to me, either. And half the time I think I'm crazy too. But now that I know that you…you actually remember some things, and now that I've seen this…"

He took a very long, deep breath.

"We were working on something. Me, your d—Dr. Betas." It felt so much better to say his name. "The two of us and the Royal Scientist. I think that's him. The third guy in the picture."

He tapped it without looking at it.

"That's…the…but that's impossible."

"Yeah, I know. I know. All of this is impossible. Heh. I've been running around for a month now, and I thought…I thought I might be the only one who…"

He sat up straight and shook his head. He took one more deep breath and began.

"I don't remember as much as I'd like. It's been a real pain. The three of us were working on something called Reset. It's something that some humans can do—it's the ability to go back and do things over. Time travel, basically. It's resetting the timeline."

Alphys leaned toward him across the table.

"Like…a video game?"

"Y-Yeah." Sans decided not to think too hard about that. "We were working with the human souls. The idea was to build a time machine, and then use the energy of the human souls to…to engineer a Reset, I think. One that we could control. Only…we needed…I'm sorry, I'm trying to remember. We needed to go back further than a Reset would allow. That—that was the point of the time machine. We were going to go back a long way. I don't remember what the original plan was. Maybe…maybe we were trying to stop the barrier from being formed? It doesn't matter now. Heh."

He stared at the glass of soda for a moment, wishing it was something a lot stronger.

"Something was wrong. The Royal Scientist had done something…I don't know what. I don't remember anything about him. A month ago we were all in the Core. There was something in there. This sort of…darkness. It might even still be there I haven't, heh, had the _guts_ to go check yet. The doctor said it was a pathway. Yeah. A path to the past. That…must have been how we were going to travel without needing to rely on a Reset or a Save point. But it was all wrong. The darkness was destabilizing the Core. It…It was going to destroy the whole Underground. We'd be in the past, but the present, everyone here…"

It was coming back to him now, the details. The events in the Core were the only things he could remember with any clarity. The fight, the doctor threatening Papyrus, the doctor calling Sans a science project. Sans begging him to stop.

The doctor coming to his senses too late.

"I stopped him. But the Core was destabilizing and…the room was coming apart. There was nothing we could do. He…he threw me in the machine and turned it on. And Dr. Betas—"

Sans's eyelights winked out.

He remembered now.

"It's…my fault."

"…Sans?"

"Oh my god, it's my fault. Betas wasn't even there. He wasn't even there but I _texted him._ I called him for help. I-I—god—I told him to find whoever he could and—him and all those other monsters—they—they never would have been there if not for me. I thought—I didn't realize what was happening until—"

"S-Sans what…what are you saying…?"

He couldn't meet her eyes. It felt like his chest was caving in. He clutched the sides of his head.

"We all fell. I was in the machine, so I think that's why I…survived. But everyone else…they just…fell."

There was a silence. Sans covered his mouth.

"And this…was a month ago."

"Yes."

"The same time I got that feeling like I'd…lost something."

"Y…Yes."

"My dad didn't disappear." Alphys seemed to be sinking in her chair. "He didn't disappear a long time ago. He died. He died a month ago."

"I'm sorry. Alphys, I'm so _sorry."_

She buried her face in her hands and burst into tears.

Sans started to get to his feet, wanting to comfort her, but he stopped. Dr. Betas had been safe. He had quit the project. He had been safe at home, recovering from an injury, and Sans had dragged him back into it. Sans had called for help and Dr. Betas—kind, loyal Dr. Betas—had answered.

Alphys's father was dead and it was Sans's fault.

He got to his feet, picked up his untouched glass of soda and poured the whole thing down the sink. Then he filled the glass with tapwater and very gently set it near Alphys. She barely seemed to notice, hiccupping into her hands.

"I'm sorry," he said again. He didn't know what else to say.

"H-H-How could I _forget_ that?" she sobbed. "How could I just _forget?"_

"The…whole world forgot," Sans said, leaning heavily against the sink. He felt a thousand years old. "Something happened to the timeline. The Royal Scientist was erased. It…seems like the timeline tried to erase everyone who fell into the Core. Only it didn't work entirely. Alphys, it's…it's good that you remember him. I thought…I thought maybe you wouldn't remember him at all."

That would have been Sans's fault too. This, though…this had to be better. Remembering someone you loved had to be better than forgetting them entirely.

Or perhaps that was wrong. Maybe it was better to forget. To be blissfully unaware. Alphys's entire world had just been devastated. If she had continued believing in the new, fractured timeline, unable to see the cracks and seams, perhaps she would have been happy.

"M…Maybe I should…leave."

"D-Don't." She looked up at him, eyes streaming. "D-Don't leave me alone yet. Please?"

"But…I'm the one who—"

"It's not your fault. Dad…Dad was…" She hiccupped and drew a shuddering breath. "H-He was such a good guy. And you were his friend. H-He would have w-wanted to help you."

Sans hugged his arms, clutching his elbows.

"I…if I had just waited…"

"Y-You didn't know what would happen. R-Right?"

"No. I had no idea."

"Okay. O-Okay." Alphys mopped at her face but the tears kept coming. "I don't blame you. I s-saw your face. You…you forgot too. I saw your face when you remembered. You looked horrified. If you didn't kn-know what would happen, then it's n-not your fault. I'm…I'm just…glad I finally…i-it never made sense. My dad wouldn't j-just disappear. He loved me."

Her voice broke again around a sob. "Th-Th-Thank you for telling me the truth."

* * *

It took Alphys awhile to calm down. Sans was patient, waiting near the sink, too unsure of himself to bother sitting down again. The pause gave him time to sort through all these new revelations and try to process them.

Dr. Betas had somehow managed to leave behind actual evidence of the original timeline. That, in and of itself, was incredible. Sans focused on that first and foremost. If he started thinking about Betas's death and his own role in it, he wouldn't be able to stop, no matter what Alphys said.

An encoded notebook and a handful of photographs. Maybe it would be enough. Maybe this was what he needed to finally put together the puzzle. The notebook was written in the same code, or language, that the doctor had always used. Now that Sans had some more of the symbols to study, he might even be able to translate it.

And he wouldn't be alone anymore. That…that was the best thing to come of all this. Miserable as this entire situation was for Sans and Alphys, at least now they both had someone to talk to.

Assuming Alphys even wanted to speak to him after this. She might say that she didn't blame Sans for her father's death, but it was a lot easier to blame a person than it was to blame circumstances.

She sniffed, sat up a little bit and scrubbed at her face. She took a long drink from the glass of water Sans had provided, then got up and grabbed a handful of paper towels to blow her nose.

"Okay," she said in a tremulous voice. She took a very deep breath and sat down again. "Okay. I'm…okay. S-Sorry about that."

He shook his head. "You don't have to apologize."

"So…" She rubbed her face again. "So let me see if I get this. The…Royal Scientist. He didn't disappear a long time ago, either."

"He disappeared the same time Betas did," Sans said carefully, sitting down again.

She nodded. "I don't remember him at all."

"You met him once, maybe twice. I don't think it matters. I think I'm the only one who remembers anything." He heaved a sigh as he settled into the chair. "And I don't remember much at all."

"And whatever he was doing, it…rearranged…what, time?"

"I…think so. The idea was to time travel. To actually _go back._ The machine was supposed to Reset, but Resetting would have erased the original timeline. But when the machine landed, it was like no time had passed at all. Instead, the timeline got scrambled. It must be _because_ he was erased. This…is a world without him. That might be the best way to think of it."

He wasn't sure he wanted to, though.

"Time travel isn't really my forte," Alphys said with a watery smile. It faded quickly. "What else was different about the original timeline? Aside from the Royal Scientist being around."

Sans was silent for a moment, considering.

"There was a whole science division. That abandoned laboratory in Hotland—it was way bigger. Room for several departments, all of us working together. Physics, chemistry, engineering, magical studies. It was…" He smiled just a little. "It was good. That many nerds in one place."

"It sounds nice. I wish I c-could have been a part of it."

"You were. You interned there. You hung out in the robotics department a lot."

"Heh. Me, interning for the Royal Scientist?" She toyed with the glass of water, tilting it back and forth. "It's…weird to hear you talk about me like…like it was a totally different version of me. Robotics is my thing, though. M-My passion. I've been working on…well, it's a secret, actually. An independent robotics project."

"From what I remember, you were pretty brilliant. I doubt that's changed."

Sans paused, debating whether or not to push this. She was in such a fragile state. He didn't want to push too hard too fast, not with the weight of her father's death hanging on her.

"Look, we've…had a pretty rough month," he said slowly, picking over his words. "I've been working on trying to understand what happened. Trying to scrounge together what information I can. Maybe…see what I can do to fix it. And from what you've told me, you've been having a bad time too."

She groaned. "It's like I said. I really thought I was going crazy. Like…I'd woken up one morning and someone had shifted all my furniture one centimeter to the right. You don't really notice, but something still seems off."

"Yeah. Heh. Wow. That's the perfect way to describe it, isn't it?"

She smiled faintly at him.

"Maybe…if you don't mind…I mean, I don't want to push you, but…" Sans rubbed the back of his neck, fingers clicking against his vertebrae. "I had no luck with any of this till I knocked on your door. If you're willing, maybe we could…work together? I, heh. I could definitely use an engineer's insight on fixing the machine."

"I'm nowhere near my dad's level," she said glumly. "But I want to figure this out. No, I _need_ to. I need to understand what happened to my dad."

She frowned abruptly.

"To see if…maybe there's a way to undo it."

It was too much to hope for, too much to even think about. Sans knew better than to get his hopes up, but the idea of it had crossed his mind—the idea of going back to that night in the Core. It counted on too many ifs—if they could fix the machine, if they could actually go back, if the doctor could even be stopped. Sans didn't understand enough about what had happened yet. Later. Later, when they had more information, then he would let himself think about this in greater detail. Then he would let himself hope.

"One step at a time," he made himself say. "For now, I think that notebook is a good lead."

"Can you read it?" Alphys asked, flipping it open again.

"No…" He took it and frowned at the symbols. "But…I'll be able to. It's like a language. Each symbol represents a letter. I know I _used_ to know it. Heh. I wonder how many layers of redundancy you can get with that."

Alphys snorted. "I know you know you think you know you used to know?"

He chuckled a little.

"I like it. But yeah. Like, this one is a G." He tapped a hand symbol with the index finger pointing upward. "It's the first letter of his name. The doctor—er, the Royal Scientist. And this one…"

His finger settled on a skull and crossbones symbol and he trailed off, frowning. There was something about that symbol. The skull. Something dangerous. Something…

He shook his head.

"An N. The more I look at it, the more I can figure it out. I wonder if your dad wrote this?"

"The letters on the front look like his handwriting."

"Do you…mind if I borrow this?"

"Go ahead. Do you want the pictures too?"

"Oh…" Sans looked away. They were the only pictures he had seen so far of Dr. Betas. Seeing them solidified Betas in his head. His friend, his colleague.

"Nah, I…they're yours. He's your dad. You said you couldn't find many pictures of him, yeah? You should keep them."

Alphys watched him for a moment. He saw tears prickling at the corners of her eyes again. She wiped them away before they could fall. Then she slid one of the photos toward him. It was the one with the three of them.

"Here. He might have left it for me, but this one is yours, I think."

He picked up the photo. It was as hard to look at as before, but…

But it was him and Betas and the doctor. It might be the only thing in the world that showed the three of them together. And it was the only hard evidence that the doctor had ever existed.

It was proof that Sans wasn't crazy.

He smiled despite himself.

"Thanks, Alphys."

She smiled back.

* * *

That night, Sans dreamed of static.

He wasn't sure where he was. It was some kind of abstract landscape, crafted from static and television snow and glitches. The sky fizzled and crackled, the ground tore. Objects glitched in and out, left and right, skittering back and forth like nervous insects.

Sans looked down at himself. He was solid, but somehow that wasn't comforting.

It didn't really feel like a dream or even a memory. It felt more like…a place. Something was hissing loudly nearby like a badly tuned radio. Sans reached up to rub his temples. Whatever this place was, it hurt. The glitches were too fast for his eyes to track, the noise was too loud. Sometimes the static would form shapes, but Sans could barely make them out. A teardrop. A hand sign, the first two fingers raised and spread into a V-shape. A skull and crossbones that kept growing in size, snarling. A sound, sharp, nearby, unforgettable, that made all of his bones prickle with terror.

"I don't…" His voice came out garbled. He grimaced, the static seeming to crackle inside his skull.

"I h-haven't learned the signs yet."

The noise and static seemed insistent. Angry, almost.

"Stop."

Instantly, the static faded. The world crackled and then winked out, as if someone had switched off the TV. The darkness deepened.

He remembered this darkness.

"Nn…"

He looked around but it was pitch black all around. No light, no features of any kind, no variations. Just darkness.

"Wake up," he whispered. "It's a dream. Just wake up, wake up, wake up…"

He turned in place, trying to find anything, _anything_ to focus on, any change in the dark, any speck of reality that he could grab and hold onto.

"This was supposed to go away," he said, and his voice fell dead in the nothing. "You said you would fix it."

Something touched his shoulder.

Sans jolted awake. He had time to notice that his bedroom was cast in a pale blue glow before he teleported.

He landed in Waterfall, in the small cave with the bench and the single echo flower. This had become his go-to place for random teleportations. It was small, out of the way, and for some reason, always felt safe.

He sank into the bench, gasping for breath.

"Damn," he said between breaths. "Damn, damn, damn…"

The echo flower spoke the word back to him over and over. He ignored it.

"Just a nightmare," he muttered. "It was just a nightmare. Just…haaah. Nightmares now too, Sans?"

He dragged his hands down his face.

"No rest for the weary, I guess."

He waited for the panic to subside. It took awhile, but there was no sense in trying to teleport when he was this out of it.

The dream was slipping away from him. He remembered static and darkness. There had been a sensation like something was trying to…talk to him, almost.

Whatever it was, it hadn't seemed very friendly.

"Just a nightmare," he said once he could breathe steadily again. "Just another thing to deal with, right? Whatever."

He looked over at the echo flower.

"I want to go home now."

The flower agreed.

Sans teleported and landed on the roof of his apartment. He sighed. One day. One day he would actually be able to land in his room. He trudged back downstairs. At least he had his house key. He had taken to sleeping with it these days for this exact reason. As quietly as he could, he crept back into his room and buried himself under the sheets.

He slept no more that night.


	4. Inheritance

.

 **ENTROPY**

* * *

Chapter 4: Inheritance  


 _Don't give up wherever you are, okay?  
_

* * *

Sans spent the next few weeks poring over Betas's notebook, struggling to translate it. He had blithely assumed that once he got a good look at the symbols that he would start to remember their meanings. He was right, but remembering the language was as slow as remembering everything else from the old timeline.

He started a second notebook and began piecing together a glossary. Once he had enough of the symbols memorized, he started copying Dr. Betas's notes over into normal letters, leaving gaps in the words for symbols he hadn't translated yet. Sometimes he could figure out words just from a couple of letters, and from there, he would be able to translate other symbols.

It was slow going, much slower than he would have liked. It didn't help that Betas had made a few spelling errors, and sometimes used a form of shorthand that neglected some characters entirely. Sans had to rely on contextual clues, some of which made very little sense, given the large gaps in his memory.

In between translating the notebook and everyday teleportation practice, Sans was usually with Alphys. A few days after their first meeting, Sans went back to her apartment. He helped her clean the place up while they discussed details they could remember and proposed theories. A day or two after that, Alphys came to Sans's place while Papyrus was out so she could take a look at the machine.

"This is…pretty bad," she had said after less than thirty seconds of looking it over.

"Do you think we can fix it?"

"I mean…maybe?" Alphys had rubbed at her head spines, a nervous habit she shared with her father. "I-I need to understand what I'm working with first and foremost. This isn't like a-anything I've ever seen before. Do you have the original blueprints?"

"No. I'm guessing they were eaten up by the timeline."

"That's gonna make things a lot trickier."

In the meantime, real life was starting to creep up on them both. Alphys's leave of absence had run on long enough that the university had started to call her, asking when or if she would be returning. Several of her professors were concerned as well. Alphys returned to school the following week, promising Sans that she would work with him every chance she got. But if Sans remembered correctly what the final year of college was like, that wouldn't amount to very many chances.

Sans had problems of his own. He was out of a job. He had barely noticed at first, too busy studying the timeline and teleporting all over the Underground, but now it was over a month later and the money was starting to run out. Papyrus worked a sort of…pity job for the Royal Guard, which was to say that he made excited faces at guards until they took pity on him and paid him to run errands. It certainly wasn't going to be enough to pay rent or sustain them both in any capacity for very much longer.

After having to worry about existential threats for so long, suddenly having to worry about money again was both incredibly mundane and incredibly frustrating.

He would need a new job.

The search seemed futile right from the get-go. It had been a combination of luck and charm that had gotten him a job with the science division in the first place. The doctor had liked him. Now, though, all Sans had to show for all of that was several years of unemployment and an unfinished PhD. All of the science labs and research organizations that he looked at made it very clear that they had no interest in an unemployed college dropout. He couldn't even call in a few favors, since he no longer really had friends.

He gave up on finding a job in any sort of scientific field pretty quickly, but there was always the Core. The Core was always hiring people, mostly for odd jobs. The complex inner workings were left to the real professionals, but you didn't need a degree to recalibrate a few puzzles. A trained Froggit could do it.

Odd jobs would sustain them for a little while, but eventually Sans would need to start thinking long-term.

"YOU? Get a JOB?" Papyrus had exclaimed when Sans had told him. "Brother, I am so proud and impressed! After all this time, you FINALLY wish to pursue employment!"

"Yeah, heh," Sans said, rubbing the back of his skull. "After all this time. Figured I should take responsibility, yeah? I _am_ the older brother. I should act like it."

Papyrus scooped him up into a hug.

"I AM SO HAPPY FOR YOU, BROTHER! I will help you in any way I can! Just say the word!

Sans hugged him back, smiling faintly. He hated lying to Papyrus like this, but what could he do? How could he explain? Papyrus still worried about Sans's new teleporting ability, even though he tried to hide it, and even though Sans had shown he could mostly control it.

It had to be better to leave Papyrus in the dark about the old timeline; about everything that had happened with the machine and the Royal Scientist. Papyrus would _believe_ Sans—he always did—but he wouldn't understand. Sans didn't want to do that to him. Especially not when all of this wasn't even close to over yet. Time timeline might seem stable for now, but there was still so much that Sans didn't understand. Whatever the doctor had actually done, it had scrambled up the timeline, and that couldn't possibly be…healthy for existence. The timeline might come undone at any moment, if it wasn't in the process of it already. No, this wasn't over yet. Sans still had a lot on his plate.

And of course, now there were the nightmares.

They weren't frequent. Maybe once or twice a week. Sans was no stranger to odd dreams and nightmares. Who didn't have the occasional nightmare, after all? And scientists were certainly prone to the occasional stress dream.

These nightmares…were different. They were like nothing Sans had experienced before. There was always the static, the glitching, like Sans had gotten stuck inside a broken computer monitor. Inverted colors, spatial distortions, endless fractals. There was always the sensation that something was trying to communicate, to _reach_ him, but if Sans ever discovered what it was, or what it was trying to say, he lost it as soon as he woke up. Waking up was always jarring. Twice now the nightmares had triggered a teleportation—the first time right as he woke up, and the second time in his sleep.

The third time, Sans snapped awake, already out of breath from trying to escape the static. The thing in his dream was angry, so _angry,_ and if it got a hold of him he was sure it would hurt him. The next thing he knew, there was the sound of shattering glass as a storm of bone bullets broke his bedroom window and punched several holes in the wall.

Sans sat up in his bed, hand still outstretched toward the window, breathing fast, eyesockets wide. Something nearby was glowing a faint blue.

He was awake. In his room in his apartment in New Home. He had just used his magic for the first time since the incident at the garbage dump.

"Oh no…"

He could already hear Papyrus thumping around in his room.

"SANS?" came his voice, muffled by the walls.

"Shit—y-yeah, I'm okay, bro!" Sans called back, scrambling to his feet. "Dammit, dammit…"

He crossed to the window, willing the bones to vanish. The blue glow disappeared as well. Sans grimaced as he looked at the damage, trying to think of a good excuse. Papyrus's footsteps were coming down the hallway. Sans put on what he hoped was an affronted expression as Papyrus opened the door.

"Sans! Is everything alright? I heard something break! What—what on EARTH happened to your window?!"

"C-Can you believe this?" Sans said, hoping his voice sounded appropriately bewildered. "Some neighborhood kids fighting in the middle of the night. Suddenly all these bullets come in my window. Jeez. Kids these days, no…no control over their magic…"

Sans rubbed his arm, guilt tying knots inside him. Papyrus looked appalled.

"Are you hurt?"

"No, I'm fine. Heh. Real rude awakening, though."

"EXTREMELY rude!" Papyrus said, putting his hands on his hipbones. "The nerve of them! Did you see which way they went? The Great Papyrus will bring them to justice!"

"Uh, I—toward the street, I guess?"

"Stay here, Sans! Your amazing brother will return soon! And come away from that window before you step on the glass!"

Papyrus was out the door before Sans could say anything else. Sans listened to the front door slam and slumped a little, looking at the broken window and the glass all over the floor. The landlord wouldn't be happy, and they were already in hot water with him.

Sans stepped delicately over the glass and went out into the hall to find a broom. Once he found one, he went back and started sweeping up the glass as carefully as he could.

This was unsustainable. After throwing a wave of bones at an innocent ghost that time, Sans had taken to just not using his magic. The teleporting was the priority, and unlike teleporting, with magic you could simply decide not to use it. But this couldn't go on. Sans had just as little control over his magic as he'd had over the teleporting when he first stepped out of the machine. Whatever force had given him teleportation had also given him a power boost.

Uncontrolled magic was just as dangerous as uncontrolled teleportation, especially for someone like Sans. If he was going to keep having nightmares so bad that he felt the need to attack helpless windows, then one of these days _someone_ was going to get hurt. That someone could be Papyrus.

He needed to get this under control, just like he had with the teleporting. And he would need to figure out what the deal was with that odd blue glow.

Sans swept up the last of the glass and dumped it into a garbage can. Then he went and found a bit of cardboard that he could tape over the broken window. He was finishing that up when Papyrus finally returned.

"Hey, bro." He smiled. "You find the hoodlums?"

"Alas, I didn't," Papyrus said, looking more upset than Sans had expected. "Did you clean up the glass already? Sans! You could have waited and let me do that!"

"I figured you might be tired after chasing down rude teenagers," Sans said with a shrug.

"The Great Papyrus is NEVER tired!" He folded his arms. "Tomorrow I am going to have a talk with the neighborhood committee! We can't have monsters running around willy-nilly, throwing BULLETS into people's bedrooms!"

Sans sat back down on his bed with a sigh. "Eh, it's not a big deal, bro."

"It IS a big deal! Monsters who don't have control over their bullets is a VERY big deal, brother! Especially in OUR neighborhood!"

Sans flinched a little. "Yeah…true…but hey, don't worry about it. I'm sure after this they'll realize they've got a lot left to learn."

"And what if they don't? So many monsters are satisfied to just throw their bullets around like CONFETTI! I'll never understand why people don't appreciate PATTERNS more! Someone could have gotten hurt tonight because of that kind of attitude! Sans, what if…"

Sans looked up when he heard Papyrus's voice waver, just slightly.

"What if one of their bullets had hit you by accident? You were asleep. You are very good at dodging, brother, but even you can't dodge in your sleep…"

"Then, uh. I guess I'd be pretty _boned,_ huh?"

"That is not funny, Sans."

"Yeah, I…I know. Sorry, Paps. I just don't like seeing you worry."

"Of course I worry!" Papyrus crossed the room and sat down next to Sans on the bed. "I am your brother, after all. It is my job!"

Worrying was supposed to be the big brother's job, not the younger brother's. Sans rubbed at the spot between his eyesockets with one finger.

"Well, I didn't get hurt, and it's not gonna happen again. I'm fine. I swear."

Papyrus slung an arm around Sans's shoulders and pulled him closer. Sans leaned against him stiffly.

"It just bothers me," Papyrus said, indignation in every syllable. "How could monsters be so RECKLESS, not knowing who is nearby? Having control over one's magic is paramount!"

Sans felt worse and worse with every passing second.

"Yeah. Not everyone is as cool as you, bro."

"Oh, of course I don't mean YOU, Sans! These, ah…'shortcuts' of yours, it's all still quite new to you, and you have made so much PROGRESS! I know you are trying very hard."

Sans closed his eyesockets and settled more comfortably against Papyrus, tired. At least the fear from the nightmare had dissipated. "Heh, it's fine. I know what you meant."

"Maybe once I have become famous and renowned throughout the Underground as the greatest member of the Royal Guard, I could offer magic lessons!" The indignation was abruptly gone, replaced with excited optimism. "I could train monsters how to use their magic with SKILL AND GRACE! Then incidents like this would never happen."

Sans smiled a little, pretending to be half asleep.

"You'd make a great teacher, Paps. Better focus on getting into the Guard first, though."

Sans yawned pointedly. Papyrus took the cue and stood up.

"And in the meantime, you should focus on getting back to sleep! Do not fear, brother! The GREAT PAPYRUS will make sure no further weirdness happens tonight! You just get some sleep! I know you need it. You've been very tired lately."

Papyrus never missed anything, no matter how hard Sans tried to hide it. He said nothing, just looked up at his brother and gave him a weary smile. Papyrus smiled back, then shot another look at Sans's busted window and stifled a sigh.

"Goodnight, Sans. Sleep well!"

"Night, bro."

Papyrus left. As soon as he was gone, Sans's smile faded and he got to his feet. No point in trying to sleep anymore tonight. Papyrus would be up the rest of the night, patrolling the apartment for any further "threats;" Sans might as well stay up too. Call it an act of contrition. He hated this. He hated lying. No one respected magic like Sans did, and yet _he_ was the one with the least amount of control.

Papyrus would probably be willing to help, if Sans could only tell him. But that just wasn't an option.

Sans sat at his desk, dug the Reset notebooks out of a drawer, and went back to translating. The photograph was between the first two pages of Betas's notebook. Sans picked it up and looked at it, frowning against the dark. He didn't want to turn a light on and make Papyrus think he was still up.

The picture had gotten easier to look at, except for when Sans tried to look at the third figure. The doctor. Looking at him was like trying to look at something faint and far away, something that only existed when you were looking just slightly to the side. Even trying made Sans's skull start to pound.

Sans sighed heavily and leaned back in his desk chair, tossing the photograph onto the desk folding his arms behind his head.

"You're dead, Doc. So are you haunting me? Is that it?"

The photograph didn't answer.

* * *

Sans woke up at his desk the next morning, neck and arms aching from the odd sleeping position. He waited until he was sure that Papyrus was out of the apartment before leaving his room. After a quick breakfast and plenty of coffee, Sans got dressed, put on a coat and teleported.

He appeared in a large clearing out in the snowy forests beyond Snowdin. He looked around, blinking in mild surprise.

"Wow. Nailed it for once."

The problem was finding a good place to practice. New Home was out of the question. Hotland was too heavily trafficked. Waterfall was too cramped and narrow. The Snowdin region was the only real option, and even then, coming up with a place that was both large and out of the way hadn't been easy. This clearing was deep in the woods, at least three miles from Snowdin. There were plenty of monsters who frequented the forest, particularly roving groups of teenagers, but as far as Sans could tell, this place was virtually unknown. Sans had found this place a week or so ago during a random teleportation. He was pretty sure that at this point he had seen most of the Underground.

With any luck, no one would ever know he had been out here.

"Alright then," he said to himself, rubbing his hands together and looking around. There was a small outcropping of rocks in the clearing, as well as a couple of tree stumps. They should make for decent enough target practice. It was almost amusing. Sans had never needed target practice before now.

Sans made a quick circuit of the clearing, just to double check for any sign that people had been this way. There was nothing. Not so much as a footprint or a broken branch.

He was stalling, he knew.

"Waiting won't make it any easier."

He came to a stop and raised a hand toward one of the tree stumps. His nerves were jangling, and no amount of deep breaths was settling them. He had to just do this.

"Start small. Easy."

It was always so simple, calling on his magic. It never failed to surprise him, despite having full access to his magic for almost two years now.

Bones erupted from the ground in a wave, bursting through the snow. Several bones exploded into the tree stump, sending bits of wood and bark flying in all directions. Sans ducked as a chunk of bark sailed over his head to land in a snow drift behind him. He lost his footing and went down in the snow.

When he looked up there was a line of huge bones between him and the stump. There wasn't much left of the tree stump, and the ground had been torn up like a runaway train had plowed through.

At least his aim was decent.

"Welp."

The feeling of the magic was as intense as it had been last night, and the time before that in Waterfall. It felt like there was a bomb in his chest trying to go off.

Sans pulled himself back to his feet, dusting snow off his pants.

"Okay. Okay. Let's try that again."

He took a breath, planted his feet and summoned his bullets again, trying to focus on sending them through the air this time. The bone bullets obeyed, but the force sent him skidding back a few inches. This time he stayed standing. Bones appeared in the air and shot toward the stump like missiles, striking the wood with explosive force. Whatever was left of the stump was smashed to smithereens.

"Still too much." He shook his hands out; they were prickling with magical energy, almost itching.

He took another breath. This was…tiring. Moreso than it should have been. Using his magic had never been _tiring_ before. There was a dull sort of ache starting in his chest, almost like his soul was in pain.

"Alright. Let's…try to ease up." He raised a hand and pointed at the rock outcropping. "Just one bone. Here we go."

He concentrated. A mass of bone bullets appeared and shot into the rocks, some of them sinking several inches into solid rock. There was a crack like a bolt of lightning as one of the rocks split in two. Sans flinched at the sound. His hand dropped to his side and he braced his hands on his legs, breathing hard.

His bullets were so much stronger than they had been before he had ended up in the machine. This was absurd. Since when could monster bullets break solid rock?

"I don't…get it." Sans stood up straight, frowning, watching as the bones slowly disappeared. "This is more than just augmenting my magic."

That pain in his chest—in his soul. Each time he used the bullets, it felt like it was _overflowing._ Like he was just barely holding back a flood. It reminded him of the experiment, when the doctor had "fixed" his soul. It was the same feeling of his soul not being…big enough, or strong enough to handle all the extra magic, like it was about to burst at the seams. But at the same time, it was different. The feeling was in reverse, an outpouring of energy as opposed to an intake. If he were to drop any pretense of control and just let the energy out, all at once…

He didn't want to think about it.

Sans looked at his hands. The occasional tiny white spark jumped between his finger bones.

It still didn't make sense. The machine imbued everything inside it with magic, and that was clearly what had happened with Sans. But if this were purely a case of Sans gaining extra magic, he shouldn't have ended up with teleportation abilities. He shouldn't have ended up with nigh-uncontrollable bullets. Bullets came naturally to a monster, even to one like Sans who had only really been using them for a few years now. It was like Papyrus had said. Control over one's bullets should never have been an issue.

There was something else at work here. Some side effect of traveling through spacetime that he and the doctor hadn't counted on. Or maybe the doctor _had_ counted on it. Maybe all of this was just a parting gift to his "favorite" scientist.

"Nah." He shook his head. It was easy to feel bitter about the doctor, given that most of the memories Sans had of him came from the last few minutes before everything went wrong. It was easy to see him as purely a terrible person.

"It's not that simple though." He smirked, though nothing was particularly funny. "I might not remember, but you weren't a bad guy. Not the whole time. If you were, I wouldn't have bothered trying to…"

He was doing it again. Talking to nothing. He sighed and fell silent, giving his head a shake to clear the cobwebs. There was work to be done. Learning to control his magic could very well take months, just like the teleportation. He had to get started.

"One bone. Just one."

He raised a hand toward the rocks again, concentrating. One bone, one bone. He focused. Then he called on his magic.

There was a sudden, sharp pain in his left eyesocket and then… _something_ appeared in the air above him. Something large enough to cast a shadow.

He had just enough time to glance up and see what it was before it made a _sound._

That sound really was unforgettable.

"Wh—"

There was a flash and a beam of light—brilliant white and crackling with electric blue—shot out of the thing's jaws toward the rock outcropping. Sans raised his free arm to shield his eyes and heard the beam shatter the rocks and keep going. The beam struck a tree and Sans _felt_ it cut the tree in two.

A second later, the beam faded. There was momentary silence before the tree creaked and then fell, the impact shaking the forest floor.

Sans peeked above his arm, shaking. Half of the rock pile had been turned to powder. The snow had melted in a line leading from Sans to the fallen tree, and the ground there was charred. He looked up at the thing, the _bullet,_ still floating above him as it closed its jaws once more.

It was a skull, large enough that Sans could have fit in its mouth. There was something canine in its appearance, but the seam along its muzzle and the swept back spikes at the back of its head made it look almost dragon-like. Nothing in the Underground looked like this thing, but Sans had seen it before. He had seen it plenty of times. You didn't forget something like that, no more than you could forget the horrible sound it made.

"Gaster Blaster," he said as he remembered its name.

He abruptly went still.

Then he sat down hard.

"Gaster Blaster," he breathed. "G…Gaster. _Gaster._ That…th-that was his name."

He looked up at the skull above him.

"That was your _name._ Gaster."

The skull winked out of existence. Sans reached up and clutched at his head. Another gap had been filled.

"Oh my god. Gaster. W.D. Gaster. Wingdings. Your name, the language you used. Your bullets. You…you turned one of your bullets into… _that."_

The skull and crossbones symbol. The letter N.

He covered his mouth with both hands, staring at the devastation in front of him. The fallen tree was smoking from the hole that had split its trunk in half.

"H-How did…how did I end up with…?"

It made no sense. It made no _sense._

Sans squeezed his eyesockets shut. His left socket was aching faintly, but he couldn't think about that right now. He had the doctor's name now, but learning it had only raised more questions.

"Gaster…" He said the name again just to say it. He had to keep saying it. He couldn't forget it, not again.

"You were outside the machine. You fell…"

Sans looked at his hands again.

"But I ended up with your bullet. The weapon you made. This…"

His hands started to shake.

"This…isn't even my magic, is it?"

That explained it. Why it was all so powerful, so volatile. He had Gaster's magic. Not all of it—if that were the case, Sans's bullets would have changed from bones to symbols. This was just a piece. A fraction of the kind of power Gaster had wielded.

But _how?_

It made no sense.

This had never happened before, never in the history of monsterkind. A monster's magic wasn't some independent force that could survive outside of the monster's soul. Monsters couldn't just absorb each other's magic any more than they could absorb each other's souls. It just didn't work like that. When a monster died, their magic vanished and what little physical matter made them up became dust.

When a monster died…

Sans dropped his hands into his lap, gaze sliding out of focus. His fingers curled. Something else clicked into place.

"He's not dead."

* * *

"Gaster, Gaster…" Alphys scratched her chin with a blunt claw, frowning. "No, it's not ringing any bells.

"It was the name of the Royal Scientist," Sans said, setting the translated copy of Dr. Betas's notebook in front of her. "The doctor's name. I remembered it yesterday."

Her eyes widened in disbelief. "You _remembered?_ Holy crap! Sans, th-that's amazing!"

"It gets better." He smiled faintly. "Once I'd remembered his name, I remembered the rest of the symbols too. Spent the rest of the day finishing the translation."

Alphys flipped open the notebook and started reading. Sans took the opportunity to finally sit down, but he couldn't help fidgeting with nervous energy. They were in Alphys's apartment, back at the cramped little table in her kitchenette. Alphys was neglecting her homework to meet with Sans, but Sans figured this was probably worth it. It had been several days since they'd had a chance to talk, and so much had happened.

"We learned the language—me and Betas. In order to keep the research in-house. And it just made it easier to talk to him. He had this sort of visual way of speaking, always moving his hands. Most people had trouble understanding him."

"What triggered all these sudden memories?" Alphys asked, not looking up from the notebook.

"I don't know. Just had a lucky revelation, I guess."

There were certain details he wanted to keep to himself. For now, at least. The fact that he had barely any control over his magic wasn't something he wanted spread around. Particularly if that magic wasn't technically his own.

"Dr. Betas wrote it all down." Sans's smile turned sad. "He was smarter than me. He knew this would come in handy someday."

The truth was, Dr. Betas hadn't trusted Gaster, not in those final months. Sans, on the other hand, had trusted Gaster too much. It had never even occurred to Sans to write down a full account of what they had been working on, or to try and leave clues for himself should anything go wrong.

That was exactly what Dr. Betas had done. The notebook was a detailed description of their research, compiling everything they had learned about Save and Reset. But it was more than that. It was also an account of Gaster's slow decline, of Dr. Betas's doubts about the project, of several key problems and negative outcomes that he had postulated. Dr. Betas hadn't known what Gaster was planning, but he had guessed that a Reset wouldn't just rewrite the timeline—that it would do so at the expense of the original timeline.

"He figured it out before I did. And he took steps to try and fix it, sorta." Sans couldn't stop fidgeting. "He realized that if the world Reset, then no one in the new timeline would have any memory that it had happened—because they're all new versions. So how do you let the new version of yourself know what's going on? Betas would have spent those last few months writing all this down and coming up with a method that would work."

"But what method?" Alphys looked up from the notebook at last. "That's what I still don't get. How did the notebook and the pictures manage to carry over?"

Sans looked her in the eye, hoping he was right.

"Alphys," he said carefully. "Do you still have the box this stuff came in?"

"I…" Alphys frowned. "I think so…it was just a normal shoebox, though. Which…which I guess is weird, isn't it? He…didn't wear shoes."

She bit her lip and got to her feet.

"Let me go find it."

She left the kitchen at a trot. Sans waited, tapping his fingers on the table. He stared at the notebook. He had spent the entire rest of the day yesterday copying it over, translating the whole thing well into the night. If he had slept, it had been for only a few minutes at his desk. Finally, they had it all. And Sans was pretty sure he wouldn't be forgetting the symbol language after this. Not unless a true Reset destroyed all this work, and what were the chances of that?

He had translated the final page very early this morning, and it was still burned into his skull.

 _I don't have much time,_ Betas had written. _Sans just texted me. Told me to gather who I could. G is doing something. Small earthquakes all week. This is it. It's happening. It's all going to be Reset._

 _I'll leave this with Alph. Dear god let this work. Please. Let my girl be alright._

 _Alph if you're reading this: I'm so sorry. I love you so much._

 _G, if you're reading this: I'm sorry I couldn't stop you. Should have tried harder._

 _Sans, if you're reading this: g_

That was it. Dr. Betas had run out of time. He would have given the box to Alphys and then gone straight to the Core with whoever he could find.

A good monster to the end.

Alphys returned, startling Sans from his thoughts.

"Got it," she said, holding up a completely nondescript shoebox. "You've seen everything th-that was in it, though—just that notebook and the photos. It's empty."

"Let me see."

She handed him the box and sat back down, going back to the notebook.

"You think it's the box? I h-have to admit, I didn't really look too hard at it. I was too…you know."

"Yeah," he said, giving her a sympathetic nod. "But yes, I think…it has to be the box. There aren't any spells or anything like that in the notebook. Anyway, I'm not sure there's a spell out there that can hold things solid against temporal shenanigans."

"Shenanigans is a good word for all this."

Sans looked the box over, turning it around. He pulled the lid off and studied the inside. It really did look like a plain, empty cardboard box. Sans reached in and ran his fingers over the bottom. There. A weird bump in the cardboard that definitely shouldn't have been there.

"Is it okay if I, uh, like…"

Sans made a tearing motion with his hands. Alphys gave him A Look.

"Sans, I'm not sentimental about the _box."_

He snorted a little and pulled the box apart section by section until he could rip the bottom in half. A thin piece of cardboard had been folded into the box over the bottom, and it came away easily. A small electronic device fell out into Sans's hand. It looked almost like a USB drive, but thinner.

He grinned and held it up.

"I knew it. Your dad was a _genius."_

Alphys stared at the device in awe.

"What is it?"

"I have no idea." He turned it over once in his hand, chuckled and passed it to Alphys. "I'm no engineer. But whatever it is, it preserved everything in the box when the timeline fractured. Kinda like a time capsule—literally."

Alphys turned the device over very carefully, studying it from all angles. Sans could practically see the gears in her head turning. She had that look in her eye, that engineer's look, as she tried to puzzle out how the thing worked and whether she could take it apart without breaking it.

"I…if I could…i-if I could reverse engineer this…"

"Heh, if anyone can do it, it's probably you," he said, beaming at her. "But one thing at a time. Let's just figure out how it works first."

"Yeah…yeah!" She turned it over again, glancing up at him with excitement in her eyes. "Did he mention it i-in the notebook?"

"He mentioned it, but there's no designs. He just says how he's working on something that should help. Couldn't find the time machine's blueprints in there, either. Just a few drawings and equations."

"This is amazing…I've never seen anything like this, but check this out, you see this wiring work here? I-It's just like on your time machine."

"Really? How can you tell?"

She gave him a very superior look. "This is why engineers are better than physicists."

He just grinned. Damn, he had missed this. The joking, the banter, the dry scientist humor. It was like having a friend again.

"But seriously. He clearly took his cues from the time machine. I mean, o-obviously this thing isn't a time machine, but I think it must operate on some of the same principals. He took some of the ideas and miniaturized them. Ha! And I re-remember, he never liked trying to miniaturize things, he a-always said things should be just the size they are. Heh."

"I remember that," Sans said, smiling fondly. "His claws were too big for the small stuff. Wonder how he managed this thing. I just…kinda wish he'd told me."

Alphys sighed a little. "Considering what you've told me about the Royal—about this Gaster guy, he must have had his reasons."

"I know."

"I have a workshop at the university. Well, uh, haha, it's more like, l-like a shared workshop, but it…it has the tools I'd need at least. I can take this there and see what I can do. I think I can at least get the casing off. Get a look a-at the innards."

She looked up at Sans and paused, her expression becoming almost plaintive.

"Can I…keep the translated copy of the notebook, too?"

He blinked at her.

"What? Of course. That's why I brought it."

"Oh. Heh, I…okay. Thank you."

"It belongs to you. He left it to you. You can have the original too, if you want."

"No, no, that's okay, y-you keep that one. I wouldn't be able to read it anyway. I can't make heads or tails of Wingdings."

"Not many people can," Sans said, looking away. He was silent a moment before continuing. "Anyway, he left messages for you in the notebook. Especially towards the end. It's my crappy handwriting, but the words are his."

"Thank you, Sans." Alphys took a shaky breath and hugged the notebook to her chest, keeping a tight grip on the device as well. "You've been w-way too nice to me."

"Nah, it's…it's just practical, right?" He rubbed the back of his head. Part of him was still waiting for the other shoe to drop, for Alphys to finally wise up and blame him for his part in everything.

"Two skulls are better than one, right? Plus, you're the engineer."

"I'm gonna do everything I can to fix that machine. And to crack my dad's design. Imagine if we could have a whole bunch of these things!" She waved the device, grinning again. "Set these up all over and we could protect the whole Underground against Resets! I m-mean, not like that's really a huge threat, but between this and the machine, w-we might be able to set the timeline right! I-I really feel like we're getting closer to something."

"I think I might be onto something myself," Sans said. "I don't want to say too much, since I'm not sure yet, but…"

"B-But what?"

"Nah…I don't want to get your hopes up. Don't want to get _my_ hopes up, either. All I'll say is…I might be able to talk to someone who knows something."

"You mean someone _else_ remembers the original timeline?"

"Not really. I'm sorry, Al, I don't mean to be cryptic. I just don't want it to turn out to be…"

To be nothing. But no, that wasn't really what Sans was afraid of. The idea that he might be _right…_ that Gaster might be, in some sense, _alive…_

It scared him. Because that thing in his dreams didn't exactly seem very happy.

Still. If Gaster was alive, or if _part_ of him was alive…it might mean that there was hope for Betas and the others as well. Sans couldn't possibly tell Alphys that her father might be out there somewhere. Not until he was absolutely sure. And there was plenty else to worry about in the meantime.

"Hm." Alphys shrugged. "Fine. J-Just tell me if something good comes of it, okay?"

"Course. You'll be the first. Well…the only."

"Is there anything else? Have you been down into the bottom of the Core yet?"

"Not…yet. I need to find a way in first. I tell you I started working odd jobs there? I've been checking the lower levels when no one's looking, but the layout is different. I only ever saw that part the one time, but…bottom line is, I'm gonna need another way in."

He would need to teleport, and precise though his aim had been lately, he didn't quite trust himself to not embed himself in an elevator shaft. Or to just drop himself right down into the darkness again, assuming it was still there. It was the same problem with the laboratory in Hotland. He needed a few more days to practice, then he would finally be able to get into the basement.

"Hurry up and wait, right?" Alphys said, opening the translated notebook again.

"Pretty much. Anyway, I'll leave you to it. You've got a ton of homework, right? A _skele-ton."_

She laughed. "One more semester and I-I'll be free! Heh. Uh. Hey, you know, I've got some time i-in the afternoon tomorrow, if, uh…I know there isn't t-too much else we can do right now where the, where all of this is concerned but, um, maybe, if you wanted…"

She was fidgeting and blushing. Sans waited patiently. She would talk herself around to it eventually, or talk herself out of it, and he had figured out by now that pushing her didn't work. No more than it ever had with her father.

"Uh, never mind, sorry, I forgot what I was going to say. Haha, I'm such a scatterbrain…"

"Hey, it's okay. I'll be free in the afternoon too, so…if you wanted, I could come by and we could talk shop. Or we could just hang. Not gonna lie, I…I haven't gotten to just 'hang out' with anyone but Paps in a long time, and all my old friends are kinda…gone, so."

There was an awkward silence. Alphys chewed her lip.

"Do you…like anime?"

He grinned.

"Never seen any…may."

"Pfft. That was bad even for you. Alright then! I can think of one off the top of my head that I've just _got_ to show you…"

* * *

It took several more days for a nightmare to come. Sans was ready for it.

No two were ever exactly alike. There was always the static, the broken imagery, but the patterns they formed were always different.

This time Sans was standing in the middle of a vast, glitching, inky lake. He recognized this place, sort of. This imagery was lifted from an old, old nightmare. Monsters would tell their kids stories of the vast underground lakes that were rumored to be hidden somewhere beneath Waterfall, somewhere down in the abyss where the water flowed away into the dark. Always be careful when you go to Waterfall, children. Anything could be down there. As a child, Sans had envisioned endless black lakes, so dark you couldn't tell which way was up. Full of creatures neither monster nor human.

The water came up to his knees and seemed to be rising, slowly. Only it wasn't water. Sans wasn't sure what it was. It was thick and oozing, like tar. Visual tearing flickered across the surface like a sheen of oil.

"Okay. Okay, it's a dream."

His voice felt like the only real thing. Speaking made his jaw feel strange, like it was gummed up—almost like the ooze had already reached his neck. He looked down to make sure it was still only at his knees.

He didn't think he'd been this scared since that time facing the _other_ darkness.

"If I'm right…" He turned in place, searching in vain for something solid. He couldn't even tell where the ooze stopped and the air began.

"I hope I'm right."

Something was hissing and crackling nearby. The sound shuddered through his skull and down his spine.

"Easy," he said, flinching. "I'm—trying. I'm trying to listen."

A small wave rose and fell in the ink, as if something large was swimming through it, leaving a wake.

"Gaster, is that you?"

The hissing stopped. Sans tried to breathe. The ink was rising.

"I remembered your name. Finally. Hhh…sorry I took so long."

The tearing in the black coalesced, flashing a white symbol. A hand sign, the index finger pointing upward. A "G."

"Gaster. That was the name of the Royal Scientist. Doctor Gaster."

A second flickering letter: two fingers raised in a V-shape, an "A." Sans smiled, but he was trembling, and the ooze was up to his waist now. He tried to move but something had wrapped around his ankles. Sans almost tripped and fell.

"Ngh…y-you know I was always slow."

A strong wind passed over the blackness, buffeting Sans and almost knocking him over. A third symbol, this one a teardrop: "S." The ooze was curling around every one of his bones and tightening, holding him in place. It took all of Sans's willpower not to fly into a panic.

"You _are_ out there, aren't you? Somehow."

Something white flashed through the darkness, almost like a face. It was there and then gone the next second. A fourth letter, a snowflake: "T."

"I-I just want to talk," Sans said, stifling a gasp as the ink reached up and coiled through his ribs. "Can we talk?"

It snaked upward, hands and tendrils of ooze grasping at him, their grip tight enough to be bruising.

A fifth symbol, another hand sign, index finger pointing to the left. "E."

"Gaster, plea—"

The ooze wrapped around his neck, cutting off the sound. Sans lost all pretense of calm. He gave a strangled shout and flailed, trying to get his arms free, struggling toward a nonexistent shore. The darkness wouldn't let go and its grip only tightened.

You weren't supposed to be able to feel pain in a dream, right?

The last symbol appeared. A sun. "R."

The darkness _yanked_ and Sans disappeared beneath the surface without so much as a splash. He tried to scream and the darkness flowed into his mouth, filling his skull.

 _No, stop, stop stop stop stop please stop._

Sans's mind seemed to fracture. The ink was all around him, flowing through him, and yet he could see himself in a thousand different places, in a thousand different memories. All at once he was back on the catwalk above the void, the Core shaking around him, only when he looked down he saw _himself._ He towered above himself. He had his back to the machine, the hatch wheel digging between his vertebrae, threatening to crack his spine. Only he was also the one holding him in place, as if there were two Sanses. He could feel his own hands wrapping around his own wrists.

 ** _I have come too far,_** he heard himself say. **_Worked too hard. I cannot stop now._**

 _Please, please stop, wake up, wake up…_

A shift and it was a different memory, his back to a wall this time as another version of himself leaned down to prod him in the chest.

 **_All that power that I gave you. Did you ever think that MAYBE I COULD ALSO TAKE IT AWAY?_ **

He flailed, but the dark was everywhere, inside and out.

 _Stop, stop it, Gaster. Gaster, let me GO!_

Something sparked inside him. Light bloomed from his left eyesocket, flickering between pale blue and yellow. The light spread, chasing the darkness out of existence, melting away the ooze.

Sans gasped as he burst upward out of the blackness, back into the air. He breathed as if he had never breathed before. The yellow-blue light swirled around him and the inky ooze retreated, leaving him sitting on something hard. The darkness writhed and churned like a mass of angry snakes, but it could no longer reach beyond the light.

Sans was safe.

He hugged his arms and glared out at the dark.

"Are…you done?" he snarled between gulps of air. "You don't…get to hurt me. Never again."

He stood, very slowly, shaking the entire time. The light stayed with him.

 _"Never_ again. Understand?"

A rumble arose from the ink, like a distant, infuriated roar.

"Oh, shut up." He swayed on his feet. "You were always…so damn petulant. Well, I'm done putting up with it. You hear me?"

"SSSSSSSSSS."

It was a voice this time, or it was trying to be. Teardrop symbols raced through the churning black. Sans stared out at it, frowning.

"What? _Now_ you want to talk like a real person? After trying to drown me?" He shoved his hands in his pockets, shoulders hunched. It was hard to stay standing, let alone to keep the light around him.

"You have a-any idea what it feels like having something ooze into your skull like that?"

Silence from the endless blackness.

"Asshole. You're lucky I need you. You broke the whole world, and now I need you to help me fix it."

"SSSSSSSSSAAAAAAAAAAAAA."

"This is wearing me out, Gaster," he muttered, covering his right eyesocket with a hand. "And here I'm trying to sleep, you know. Let's try this again. Later. When you're in a better goddamn _mood."_

"SSSSS. SSSSS."

The ooze went still, as if it was considering something. As if it was waiting. Sans watched it. He couldn't keep this up. This light was exhausting him, taxing his very soul. He needed to wake up soon.

"Well?"

There was a very long silence. Even the hiss and crackle of the constant static had faded.

"SSSS. ANNNNSSSS."

His eyesockets widened.

"SANS."

It spoke with thousands of voices. Sans looked around.

"Yeah. It's me."

"SANSANSANSANSANSANSANSANSANSANSANSANSANSANSANS."

It kept going, an endless chant from the dark, rising in pitch and volume. Sans pressed both hands to the sides of his head to try and muffle the noise, but the voices were echoing inside his skull.

"Stop, it's too loud!"

Figures were starting to appear from the ooze, almost monster-shaped. The chant went on until Sans's name became meaningless, a roar of white noise. It felt like his skull was trying to split into pieces.

"SANSANSANSANSANSANSSORRYSANSANS."

"Gh—!"

The darkness shattered.

Sans woke up on the floor of his bedroom, his blanket tangled around him. He stared up at the ceiling and it was all he could do not to start screaming or throwing bones in all directions. He covered his face to muffle the small sounds that escaped him.

That light was still there, casting his bedroom in an eerie glow. At least he finally knew where it was coming from. Another inheritance from Gaster that he had never wanted.

It was like any other magic—turning it off was as simple as deciding not to use it. The glow faded, leaving his room in darkness. Normal darkness. Comforting, even.

Sans waited until he was sure he had himself under control before he let his arms fall to the floor. He lay there, breathing. He couldn't remember the last time he had felt this tired.

"So you really are alive," he whispered. "At least sort of. You're a real mess these days, Doc."

Now that he was awake, back in the real world where some things made sense, he could sort through what he had learned. He had been right. Gaster might not be strictly alive—he might not even technically exist—but he also wasn't dead. Sans had a piece of Gaster's magic; that magic had to be resonating with whatever else was left of him. It explained the dreams.

It didn't really explain why Gaster had tried to kill him.

"He can't kill me in a dream." Sans paused and sighed heavily. "Or maybe he can. What do I know?"

Maybe Gaster hadn't really wanted to kill him. Maybe it was just…dream logic. Sans was pretty sure that Gaster wasn't literally a lake of oozing darkness, after all.

He shivered, remembering the sensation of the darkness seeping through his bones, into his skull. His fingers dug into the thin carpet.

"No. Calm down."

Gaster was still partially cognizant, though, that much was clear. He had spoken. Apologized.

Sans snorted. "Sure. Just like always. Mess with Sans all you want but, hey, as long as you apologize at the end…"

He wished he could just forget. If only Gaster had been fully erased from his memories. If only Sans had stepped out of that machine unable to remember a single thing. Then he could have just settled into this fractured timeline and gotten on with his life. But because he was aware of what had happened, he had to try and do something about it. Because he knew Gaster was out there somewhere, he had to try and find him. Not to save him. No, he was done with that.

Gaster was going to help Sans, for once. He was going to fix the world he had broken, even if Sans had to drag every piece of Gaster back together, kicking and screaming.

Sans just had to figure out how to talk to him first.

He smiled bitterly at the ceiling.

"Are you ever going to learn, Sans?"

Probably not.

Sans pulled the blanket off of his bed and curled up beneath it. He spent the rest of the night on the floor. He didn't dream.


	5. Frustration

.

 **ENTROPY**

* * *

Chapter 5: Frustration  


 _That's your cue to laugh._

* * *

Sans went to the Core.

He said hello to the few coworkers who actually knew him by name, dodged their questions and made his way deeper. It wasn't easy. The inner parts of the Core were restricted areas, and getting past the security guards and lasers took some tricky teleporting. It didn't help that the layout had changed a lot since the last time Sans had been here.

Eventually, though, the staff thinned out and most of the security became automated—just cameras and lasers. Easy enough to avoid. The deeper Sans went, the less security there was overall, and the more confusing the layout became. Sans got lost several times, running into dead ends that, as far as he could tell, served little or no purpose. There was no way of knowing how many of the changes were due to the timeline's divergence and how many were because of the Core's constantly shifting nature.

After a few hours, he finally reached one final dead end. This one he recognized. This was where the elevator should have been, but it as just a blank wall. The heat down here was almost unbearable.

Sans pressed a hand against the wall. He had no idea if the elevator shaft was back there behind the metal—all the blueprints for this part of the Core had been lost when the timeline broke. The lowest room below might not even exist.

Sans just had to hope it was.

"Moment of truth, I guess," he said, sighing.

He stepped back from the wall and closed his eyes, concentrating. His aim was nearly perfect these days—nearly being the operative word. He just had to trust himself, something he had never been good at.

Sans braced himself and teleported.

He reappeared. He could feel open air all around him, but his feet were on solid metal. Sans opened one eyesocket, then the other.

"So it does exist."

The room was exactly as he remembered, huge and cavernous, with the catwalk right down the middle. Sans kept his gaze forward, sweating. He told himself it was just from the heat.

"Just look down," he said through his teeth. "Do it."

Very slowly, he looked down.

About fifty feet below him was a floor. It glowed faintly orange from the heat. That was it: just a floor. No void, no hole, no churning darkness.

Sans looked around, as if maybe the abyss had gotten up and moved. Nothing. Just a floor. Just a huge, empty, pointless room.

"Huh…"

This wasn't what he had expected, but it made sense. Gaster was gone, and most of the things he had created were also gone. Since the Core had stayed, Sans had thought that maybe the hole in the Core would have stayed as well.

Sans felt a surge of relief. This was good. One less thing to worry about. He should have figured that the hole was gone when there were no more earthquakes, but he hadn't wanted to assume anything.

"There's one good thing about this timeline, I guess."

He stuffed his hands in his pockets and teleported, landing back in his room. He jotted down a quick map of the inner Core and a few notes in his journal, then teleported again. This time he went to the old lab.

It was as empty and unsettling as always. The only disturbance was his own footprints in the dust, two months old now.

He made his way further in, down the hall to where the elevator had been. The chalk outline was still there.

"Man, I cannot draw a straight line," he muttered, smudging the chalk with a finger. "Alright. Straight on down. Easy."

He squeezed his eyes shut and teleported again.

And there it was—the basement lab, just as he had guessed.

Like the bottom of the Core, the lab looked exactly the same. The same desks, the same hallways, the same rooms. There was an area at the back of the main room where the time machine had once stood. The slots in the wall for the soul containers were still there, though of course the souls were long gone.

Nostalgia overtook Sans all at once and his shoulders hunched a little. Memories came trickling back to him. This was where it had all happened. Where he and Betas and Gaster had worked to create scientific miracles. I had been good at first. All that potential, all the grand ideas and plans. They had really believed that they were working to free all monsterkind, when the whole time…

Sans walked to Betas's desk. It was still here, though there was about an inch of dust on the surface. The computer had long since stopped working, and Sans could hear insects skittering around inside the monitor.

Sans started digging around through the drawers. If Betas had created one box that could survive the timeline break, maybe he'd made more. The drawers were virtually empty save for some files and broken pens, as well as a punctured stress ball. He checked the drawers for false bottoms or other secret compartments, but there was nothing.

He went to his own desk next, vaguely hoping that maybe his stuff was still here. He'd left his housekeys, his files, his favorite coffee mug, pretty much everything but his cell phone and wallet when Gaster had dragged him off to the Core. But it was the same as Betas's desk—a busted computer and drawers filled with dust and scraps, as well as what looked like a one hundred year old popato chisps bag. The timeline hadn't even seen fit to keep his secret ketchup stash.

Sans plunked down into his old desk chair, sending up a cloud of dust.

"Heh. Almost like I never existed."

He wondered what that would be like. If Gaster hadn't thrown him into the machine at the last second, that would have been Sans's fate. That was certainly Gaster's fate.

Judging by Sans's dreams, not existing was extremely unpleasant.

He'd had a few more of those nightmares. Each was more frightening than the last, and Sans was making no progress in communicating with whatever part of Gaster was frequenting the "dreamscape," as it were. Sans kept trying, even though he couldn't be sure that there was even enough of Gaster left to actually _talk_ to. It did seem that Gaster was trying to reach him, but his methods were very…forceful. Sans could only ever hold his own for so long before he needed to wake up. And he always woke up more tired than when he had gone to sleep.

Sans sighed and leaned back in his chair. The longer he stayed here, the more he remembered. Down that hallway was the room where Betas had tried to talk Sans out of going after the green soul. Over there was where Gaster had thrown Betas against the wall so hard he had broken Betas's arm. Sans couldn't forget that sound. Over there was where Gaster had turned Sans's soul blue for the first time. Gaster had been so eager to teach Sans about blue attacks.

Sans realized he was clutching at his chest and dropped his hand, frowning. He needed to stop that. He needed to stop being so afraid. Having his soul turned blue was hardly the worst thing that had happened to him.

He got back to his feet and went to Gaster's desk.

As he approached, he got that feeling again. The same feeling he got in Gaster's office upstairs—a sensation of wrongness, of the world trying to fall away beneath his feet. Sans gritted his teeth against the ache in his head and kept going.

He reached the desk and gripped the back of Gaster's old chair tightly. The fabric was rotted and as dusty as everything else. Sans had caught Gaster sleeping in this chair a few times. Not nearly as often as Gaster had caught Sans sleeping at his own desk. It was a rare thing to see Gaster sleep. Sans would usually just leave him a cup of coffee and continue his work in silence until Gaster woke up naturally.

"Don't get lost down memory lane, idiot," Sans muttered, wheeling the chair out of the way. His skull was pounding, but he tried to ignore it. Gaster's computer had fallen to pieces, the monitor cracked in several places. Sans hesitated with his hands over the desk drawers. He almost felt like praying to the Delta Rune to find something, _anything._ He had been planning this day for a month now, waiting for his teleportation ability to finally be under control, so he could finally explore the two places he most needed to. And so far the entire day had been a bust.

He pulled open the first drawer. The usual: some pens, pencils, a slide rule, a few blank papers and an empty folder. Sans went through the other drawers, cursing under his breath. Nothing. More nothing. A few notes and memos written in Wingdings. Sans folded those up and stuffed them in his pocket. They were virtually useless, but they were the only thing he had found yet in Gaster's handwriting.

Sentimental value.

In one of the drawers, Sans found one of Gaster's notebooks. He'd kept probably hundreds over the years, but this was the first one that Sans had found. He flipped through to find that most of the pages had been torn out. There were singes on the scraps of paper that remained, almost like they'd been burned. In the back was a single page with actual writing on it. Sans read it, eyesockets going wide.

Entry 17.

DARK DARKER YET DARKER

THE DARKNESS KEEPS GROWING

THE SHADOWS GROWING DEEPER

PHOTON READINGS NEGATIVE

THIS NEXT EXPERIMENT

SEEMS

VERY

VERY

INTERESTING

…

WHAT DO YOU TWO THINK?

"I think I should have tried to stop you a lot sooner, Doc."

Seventeen…that would have been the last test before they brought the machine to the Core. Sans remembered it now. He had come into the lab and Gaster had announced that they were about to conduct the eighteenth test. Lucky eighteen. Gaster had called Sans "indispensable." It was probably the last good thing that had happened between them.

Sans closed the notebook and tucked it under his arm.

There was nothing else in Gaster's desk. Sans spent the next hour exploring the basement lab. All in all, it was the same as everything upstairs. Broken equipment, scattered files and documents, the assorted debris that came from years of neglect. No evidence of their work on Reset. No remnants from their research into the human souls. No sign of the Determination Extractor, or the makeshift X-ray machine they had used to strengthen Sans's soul, or Dr. Betas's device, or any of the projects they'd completed. Nothing.

Gaster had truly never existed.

All that hope and planning, and all Sans had to show for it was a single page in a notebook. Sans couldn't help but be frustrated. He had been so _sure_ that he would find some clues in the Core or here in the lab.

Sighing to himself, Sans teleported, leaving the lab to its dust and memories.

He landed in his room and immediately sank into his desk chair, dropping Gaster's notebook onto the desk. It landed on a stack of unopened mail; mostly bills, along with some passive-aggressive letters from the landlord. Sans leaned back in his chair and let his arms drape over the back, staring up at the ceiling.

His room was more a mess than usual these days, clothes and papers and trash making it hard to find the floor. No one had ever gotten around to replacing the window, so there was still just a piece of cardboard over the hole. At least Sans hadn't broken anything else in his sleep since then. Not yet, anyway.

He really wished he was better at looking at the bright side.

Things were supposed to have gotten better. That was how things worked. You put your mind to something and slowly but surely, problems would resolve themselves. But nothing was improving. Sans was as lost as he had been when he had first stepped out of the time machine. He had his teleporting under control, but the magic was another story entirely. Every spare minute he had was spent out in the frozen forest near Snowdin, practicing, but every bullet he summoned felt like a bomb about to go off in his hands. He and Alphys had been working hard, but thus far they had nothing to show for it. The time they managed to spend together usually devolved into just hanging out and watching anime. Which was fine in its own way, but not very productive.

Every moment that wasn't spent practicing magic or working on the timeline was spent working in the Core. Sans was pulling double shifts, but it didn't even matter. They were behind on the rent, and the landlord was giving them one more month to get their act together. After that, Sans and Papyrus would be out on their tailbones.

Sans couldn't let that happen. Not again.

Even sleep was no escape. The "Gaster dreams" might be few and far between, but every other night was nothing but insomnia and stress dreams. Sleeping was one of the few things that Sans was good at, but he was even messing _that_ up lately.

Sans was just…tired.

He tried to will himself to sleep, but to no avail. All he managed was to stare wearily at his ceiling for the next hour, until he heard the front door open. Papyrus was home.

"SANS! ARE YOU HERE? I HAVE ACQUIRED DINNER!"

Sans hauled himself upright, worked the kinks out of his neck and put on a winning smile. Then he went out to see his brother.

"Hey bro," he said. "How was your day?"

Papyrus grinned. "Excellent, brother! Something VERY good has happened! One of the Royal Guards has informed me that a few sentry positions will be opening up quite soon! SENTRY POSITIONS! Do you know what this MEANS, BROTHER?"

"Enlighten me," Sans said, taking a seat while Papyrus set down cartons of takeout. Sans gave the cartons a resigned look. They were supposed to be cutting back on the takeout–too expensive–but neither of them had any cooking skills. One of these days they were going to have to fix that.

"IT MEANS, DEAR BROTHER! That if I become a sentry, I am one GIANT step closer to becoming a REAL ROYAL GUARD! Imagine it! The RESPONSIBILITY! The FAME! The RESPECT! The…paycheck!"

Even Papyrus was worrying about money, despite Sans's best efforts.

"That's great, bro," he said, smiling back at his brother. The smile was fake, but the pride at least was genuine. "You're on the up-and-up. Won't be long before you're Captain of the Guard."

Sentry work…that might actually not be a bad idea. Papyrus was right–it would certainly pay better than odd jobs in the Core. And being a sentry mostly consisted of sitting around and waiting for something to happen.

"Which posts are opening up?"

"A small handful, but they're all over the Underground, even here in New Home! How lucky is THAT?"

"Pretty lucky." Sans paused, prodding at his food. Papyrus had gotten him a burger from one of the places he liked, even though Papyrus hated burgers. "Hey, bro. What would you say to the idea of…moving out of here?"

Papyrus stared at him in confusion over his box of noodles.

"Moving out? Huh! I don't know…why? Do you not like it here anymore?"

"Nah, it's not that, it's just." Sans shrugged. "You know, the window problem, and there's so many _stairs,_ and I dunno…a change of scenery might be good."

"You could do with a few MORE stairs in your life, brother," Papyrus said, squinting at Sans.

"Heh. Maybe." Sans stared at his burger, wishing he felt more hungry. "It was just a thought."

Sans could feel Papyrus's eyelights on him.

"Sans…"

"Mm?"

"Just how badly off are we?"

"It's–we're not that bad. That's not why I asked. We're fine. I told you I picked up extra shifts in the Core, right?"

"And I am pleased to see you working so hard, brother, even though I WISH you would find a real job!"

Sans just sighed.

"But I am an adult, Sans!"

"Barely."

"MY POINT IS! You don't have to lie to me, brother. I know things aren't…well…the BEST they could be right now. But if it's bad…"

"It's…fine, Paps. We've still got some time to sort things out." He gave his brother a smile. It was tired, but it was more genuine this time. "We're survivors, bro. We'll be okay."

Papyrus was silent for a minute, staring off into space and pondering.

"You know, I WAS thinking…maybe there's a bit too much extra space in this apartment! It's a bit too open, right?"

Sans looked out at the rest of the apartment. "Spacious" the apartment was not. Not an inch was wasted.

"Bro…"

"No, I think you might be right, brother! A change of scenery could be good for us both! And it might be nice to…have a different landlord." Papyrus's gaze flicked to the side in annoyance. Sans had to chuckle. Papyrus made an effort to not say an unkind word about anyone, but some people managed to push his buttons.

"We can find another place. A better place! Depending on where I am stationed when I become a GREAT SENTRY, we could move somewhere closer by!"

"You're sure you'd be okay with that?"

"THE GREAT PAPYRUS IS ALWAYS SURE!"

That was certainly true. There would be no changing his mind now.

"Alright, then. We can start looking for places."

"BETTER places!"

"Yeah." Sans had already been considering this for a few weeks now, and had even found a few places that might work. All of them quite a lot cheaper and…quite farther away.

He knew Papyrus despised Hotland. Sans just hoped he didn't have the same opinions about Snowdin.

* * *

"I have good news and bad news," Alphys was saying.

"Oh boy."

"The good news is, I managed to crack my dad's design," she went on, running her hand over her headspines. They were in her kitchen again, which had become their work area.

"N-Not literally," she said with a nervous laugh. "That would also count as bad news. It took awhile, but I finally figured out the design. It's really intuitive. It generates a very small field of temporal magic that keeps everything in the field permanent within space and time. It should continue to work for years and years."

"That's great," Sans said, genuinely impressed. It had been long enough now that he was starting to worry if maybe the device would run out of juice one of these days. "So…what's the bad news?"

"The bad news is…there's no way to duplicate it." She tapped her claws together, eyes downcast. "I can't reverse engineer it. And it's…for the same reason that I'm not sure I'll be able to fix the time machine. They both run on soul power, for one thing, and no one but Asgore gets access to the souls."

"Not even for scientific study?" Sans folded his hands under his chin, frowning. "He let us work with them all the time, before. I think…he and Gaster might have been old friends. He trusted him."

Which, in retrospect, had been a terrible idea. Maybe on some level, Asgore knew that–knew what Gaster had tried to do.

"If there was ever a new Royal Scientist, they might be allowed? But no. I mean…I assume that some of the work you guys did must have carried over into this timeline, because we understand a lot about human souls that–that, like, I don't think we would understand if no one had gotten to study them? If that makes sense?"

"Sure, I get it." Sans paused, thinking. "If it's just a matter of getting the souls, though…there…might be another way."

"Really?"

Sans just nodded. It wouldn't be too hard to figure out where in the castle the king was keeping the four souls. Sans could pretty easily teleport there and borrow one or two. He'd return them once he and Alphys were finished, and Asgore wouldn't even have to know.

Sans's grip on his hands tightened. He was pretty sure that was the most treasonous thought that had ever passed through his skull.

"Even so…it's more than just that," Alphys said, sounding contrite. "The thing is…both my dad's device and the time machine? They operate on technology that's kinda…out of this world. I-I'm guessing it's because, before the timeline diverged, you guys had all sorts of technology and advancements and such based on–on marrying soul power and monster magic and normal tech. Some of the wiring, the electrical pathways, the designs, it's all based on–on like–like what if soul energy was passing through it? Or what if a combination of soul energy and monster magic or whatever was passing through? So…even if we did, um, somehow get to use the souls, we wouldn't be able to _do_ anything with them. We'd need about ten years of working with human souls just to catch up with this stuff."

Sans was quiet, mulling this over.

He'd taken it for granted, really. They'd always had immediate access to the human souls before, whenever they wanted. Departments would pass the souls around like popcorn. You filled out some paperwork that basically meant you promised not to absorb the soul, and that was it. Even if Sans could fully remember the timeline, he would never be able to remember all the different advancements that had come about due to their studies on the souls. In only a few years, the science division had revolutionized the Underground. And the souls were always _right there_ if you suddenly had a new idea you wanted to test out.

Without Gaster, most of those advancements had never happened. And now the souls were out of reach.

"I'm sorry, Sans," Alphys said when Sans didn't answer. "I-I tried everything I could, but it's just…I don't think it's doable with what we have now."

"Nah, it's…it's okay," he said, not fully looking at her. "I know you tried your best. And I knew this wasn't gonna be easy. A timeline isn't something you can just…superglue back together. Heh. If only, right?"

"Heh. Yeah. Or, or like a jigsaw puzzle. Monsters are always good at puzzles."

"Who knows. Maybe someone will become new Royal Scientist soon?" He smirked a little, trying to imagine someone trying to step into Gaster's shoes. "Then you could go work with them and maybe in a few years…"

He shrugged. A few years wasn't so bad. Even ten years wasn't so bad. If he could just find a way to get _Gaster_ back, then everything might go a lot smoother. Gaster could still help, even if he didn't really exist.

"Hey, uh…this might be a really pointless question…"

"No such thing." He smiled faintly, remembering something. "Go ahead."

"Have you…ever considered trying to become the next Royal Scientist?"

He blinked at her.

"What?"

"I mean…" She started ticking off on her claws. "You're qualified. You actually _worked_ with the last one, even if he's gone now. You're brilliant. And you knew how the old division was run, so you could probably start it back up again. It…it kinda makes sense, right?"

Sans rubbed the back of his skull, looking away from her. Him? The Royal Scientist? It had never even occurred to him.

"Heh, Al, I think you're overestimating my skills." He couldn't help an embarrassed smile, though. It was flattering to be thought of so highly. "I'm not– _that_ smart. Not Royal Scientist material. And…in this timeline, I'm just–I gave up on my PhD and then spent the next, I don't know, five years? Doing nothing with my life. According to my brother, I never worked a day in my life until I started picking up odd jobs in the Core. As far as this version of the world is concerned, I'm…pretty much useless."

Alphys tilted her head. "But you and I know that's not true. Maybe…if you explained it to Asgore? If he was Gaster's friend, he might even sort of remember him."

Talking to King Asgore might be worth it, though certainly not because Sans was going to ask to become the next Royal Scientist.

"The fewer people know about this timeline business, the better. Heh. Can you imagine walking up to the King and telling him you're a time traveler?"

"But you have proof. Evidence."

"I have a time machine that to anyone but an engineer just looks like some kind of fancy refrigerator. And a notebook in a language no one knows, that anyone could have written." Sans chuckled. "I'd get thrown in a dungeon at best and get exiled to the Ruins at worst."

Alphys's expression seemed almost…concerned.

"So you haven't even told your brother?"

"Haaah…" Sans scrubbed at his face with his hands. "I went home that first night and pretty much had a meltdown right in front of him. He…was so worried. Everything weird that happens or that I say, it just makes him more worried. I mean…he'd _believe_ me, but he wouldn't understand, and it would just make him worry even more."

Sans paused again, folding his hands back on the table, staring at the delicate bones in his hands and fingers.

"Have you ever actually thought about…about Reset, about what it really means? That a power exists that can let someone go back in time, completely destroying the original timeline and everyone in it? That something like that can actually _happen?"_

"But it's not going to anymore," Alphys said, but he could hear the uncertainty in her voice. "With the machine busted, no one's ever going to Reset again. I mean, heck…it didn't even _really_ work this time around. Gaster sent you back a few seconds and just kinda–pulled himself out of the timeline. How did he even do that, anyway?"

"I still have no idea. But that's not the point. The point is it _does_ work. If someone really wanted to, they could just absorb the souls and Reset. Or heck, a human could come along and do it. Timelines would keep being created and destroyed, and we'd have no way of knowing about it."

Alphys was quiet for awhile. Sans said nothing. He'd been thinking about this a lot lately. Too much, really. He'd been asking himself–was what he was doing, trying to fix the timeline, did that count as a Reset? If he restored Gaster and set the timeline right again…what would happen to the timeline he was in now? Would it fold back into the old timeline, or would it just be obliterated, like Gaster had been trying to do in the first place?

"I guess…" Alphys said at length. "I guess that makes you feel pretty small. Knowing the world can just be rewritten like that."

"Yeah." He looked up at her finally. "That's a good way of putting it. Anyway…that's why I can't tell Papyrus about this. Hell, we shouldn't tell anyone if we can help it. Ignorance is bliss, you know?"

Alphys sighed and leaned back in her chair for a moment. Then she leaned forward again, giving Sans a tentative smile.

"But, hey. We're not giving up hope, right?"

"Heh. Nah. Of course not."

"Yeah! We–we can get that machine fixed and sort out this timeline once and for all. We'll figure out some way of doing it. Even if it t-takes years and we have to invent new technology to do it!"

He grinned. "Yeah. Just gotta keep a positive outlook, right?"

"Exactly! We can do it, Sans. I know we can."

* * *

"Again," Sans told himself, trying to stay upright. It was hard. He was shaking, sweating, gasping for breath. The world blurred in and out.

 _"Do it,"_ he said through his teeth and raised a hand toward a stone in the middle of the clearly. The ground around it was torn to pieces, the snow turned brown with scattered dirt, but the stone was undisturbed.

There was a rush of magic. Bones erupted in a wave from the ground and careened past the stone with the force of a tsunami. The wave missed the stone by a centimeter. A few bones clinked against it harmlessly.

The wave ended. Sans dropped his hand and braced himself on his knees, panting. The bones vanished.

"Dammit," he said between gasps. "Why are you…so bad at this?"

The stone was maybe a foot across–not even that small of a target. It had taken two weeks for Sans to hit a target three times that size, and this was taking even longer. Aiming shouldn't have been this hard, but Sans felt like he was trying to thread a needle with a cannon.

Sans took a few seconds to catch his breath, then forced himself upright. He swayed. He was pushing himself too hard, he knew, but he _had_ to get this right. He had to get _something_ right.

"Again. Come on."

He raised a hand again. The wave came from above this time, like a whip crack. The bones bore down on the stone and–

Missed.

"F–"

Sans came to three hours later, facedown in the snow. He didn't remember passing out. Not like it was the first time–probably wouldn't be the last, either.

He tried to roll over only to hiss in pain. Ice crystals had formed in some of his joints, making movement not just painful but virtually impossible. That was what he got for falling asleep in the snow. If he'd been any monster but a skeleton he would probably have hypothermia by now.

"Way to be, Sans," he muttered into the snow.

He teleported. The world tilted and then he was face down on the floor of his bedroom. Even the slight jolt of the landing hurt. He'd thaw out in a few minutes, and until then, he just had to hope that Papyrus didn't walk in. Not that Papyrus had never caught him sleeping in strange positions before.

He couldn't keep doing this to himself, but what choice did he have? Papyrus had asked him twice now if Sans wanted to come out and practice magic with him, and both times Sans had made up some kind of excuse. If he couldn't even hit a one-foot-wide stone, he couldn't be trusted around other monsters, least of all his brother. At the rate he was going, he might try to summon a couple bones and instead Gaster Blaster an entire city block.

And it wasn't like he could dodge Papyrus forever. The sentry positions weren't available quite yet, but Papyrus had started training rigorously all the same. Evaluations would be in a month or so, and that was just to be considered for the position. After that there would be actual training and testing and so on. Becoming a sentry wasn't nearly as difficult as joining the Royal Guard, and Papyrus had all the confidence in the world, but Sans could tell he was still nervous. It didn't matter how many times Sans told him that he was basically a shoe-in; Papyrus already had the combat and puzzle-making skills of two sentries put together.

It took him back. Sans remembered how nervous he had been before his interview at the science division. He would be meeting _the Dr. Gaster_ in person, someone he had respected and looked up to for most of his life. Papyrus had been there for him, walking Sans through potential interview questions and quizzing him on scientific theories that Papyrus didn't even understand.

Sans had to be there for Papyrus now, and that was probably going to mean throwing a bone or two his way. He just had to figure out how to do it without accidentally killing his brother.

By now there was a small puddle of melted snow on the floor and most of his joints had thawed out, so Sans rolled over, slowly. He sat up and leaned against his bed, bones creaking. A stray sock had gotten stuck to the back of his hoodie. Sans left it there. Three hours he had slept in the snow, yet he was still tired. He couldn't sleep, though. He had an evening shift in the Core. Maybe there would still be some coffee left over from this morning in the kitchen. He should get up and go check.

Instead, he fell asleep. He didn't mean to.

Gaster was waiting for him for the first time in over a week.

It was New Home, but all wrong. Even if Sans could ignore the static and glitching, the warped buildings and streets that sank down into nothingness, he couldn't ignore the silence. Except for the faint white noise that was always present in these dreams, New Home was _silent._ No hum of electricity or machinery, no distant chatter. Sans looked around. There wasn't a single person in sight.

"This is new…"

Sans started walking down a familiar street. Gaster would be around here somewhere, in one form or another. Sans just had to find him. Hopefully soon, so he could at least put this silence out of his mind. New Home was the largest city in the Underground–the only city, really. It should never have been this quiet. And where were all the monsters?

Gaster hovered at the edges of Sans's awareness while he searched, slipping between glitches, hiding behind dead pixels. Sans caught flickers of movement out of the corner of his eyesocket.

"This one isn't so scary," he said, knowing Gaster would be listening. "Maybe you're losing your edge, Doc."

Sans turned a corner. He heard a rustling sound behind him, like something moving through grass. The world rippled and changed, and all at once Sans was walking through Waterfall. He faltered only a little. He was in an area he knew well, a small settlement near the main waterway. It was one of the busier areas in Waterfall.

Right now, it was silent. Sans didn't see a single monster.

"Creepy," Sans admitted. "Still better than usual. What are you getting at, Gaster? Can't you just…talk to me like normal?"

A dark shape moved within the shadows. The static grew louder. Sans rolled his shoulders, trying to stay calm. Talking to Gaster had been all but torture thus far. Sans always got the sense that Gaster was _trying_ to communicate, but he did it with this dream imagery, with static and symbols. Sans could never understand what Gaster was trying to convey, and Sans had a feeling that just made Gaster more angry.

"It's been a long day, Doc," Sans said, rubbing his forehead and sighing. "Can we do this later?"

The world shifted again. Snowdin this time. Visual tearing ran back and forth through the snow. There was no one around, not even the ubiquitous dogs. Even the light above Grillby's was off. The silence was deafening.

"Alright, I get it," Sans said, hands tightening to fists in his pockets. "The Underground is empty."

He closed his eyesockets and made an unamused sound.

"I'm all alone in the whole Underground. Heh, that's not even trying to be subtle. Yeah, poor me, alone against the world. Come on, Gaster, you could have just spelled that out with symbols. Didn't have t–"

Something hit him from behind, hard enough that Sans went down, faceplanting in the snow. He rolled over and scrambled to his knees, left eyesocket coming ablaze. The world had gone dim and Sans found himself surrounded by flickering shadows.

He glared between them, trying to track their movements. Gaster tended to avoid Sans when the "eye" was alight–Sans wasn't sure why–but he had been getting bolder.

"Stop that," he said through his teeth. "Shoving people around when you don't get your way? Pretty juvenile, Doc."

The shadows hissed, swirling around him. Sans got the distinct impression that he was being circled, as if a predator was trying to find an opening. Wisps of shadow reached toward him, testing.

"Back off. Stop with the show. Just tell me. Come on, Doc, use your words."

There came the voice, garbled and full of static, scraping against the inside of Sans's skull like sandpaper. It was accompanied by the usual symbols.

"SSSSSAAANS."

"Yep. Sans. We've established that that's my name."

A tendril of shadow snapped toward him, but Sans was quick, focusing his magic. Blue light dashed the shadow into nothing. Sans raised a hand. He wondered if he could summon Gaster Blasters here. He wondered what that would do to whatever fragment of Gaster he was dealing with. It would give the old bastard something to think about, certainly. It might even serve to wake Sans up.

"LIIIII. SSSSSSSSSSS. TENNN."

"Listen?" Sans frowned, taking a second to make sure he had understood. "I'm _trying,_ but you're not making any sense. You _never_ make any sense. So you show me an empty Underground, what, to try and convince me I'm all alone? You trying to isolate m–?"

"NO."

Sans paused. That was the first time that Gaster had actually answered back. Had actually proved that he really was listening.

Maybe this was progress.

"Then? What?"

The shadows roiled and the voice within them split into several voices, all snarling and growling. Frustrated. Gaster was just as frustrated as Sans was.

"SSSSSSS. EEEEN," said one voice.

"IT," said another.

"Okay," Sans said, raising both hands in a placating gesture. He could cut Gaster some slack. It wasn't like this was a good time for either of them. Or, considering all the voices, _any_ of them.

"Okay, let's just take it easy. Slowly, yeah? 'Seen it'–so what have you seen?"

Beyond the shadows, the world rippled again, the image shifting to an area deep in the woods outside of Snowdin. There was a huge purple door against a cliff wall. Sans squinted, trying to see past the shadows. It looked like the door was ajar.

"I don't get it," Sans said quietly. "I've never seen a door out there. Where does it lead?"

Gaster's voices started chattering, rapid and incoherent.

"Slow down. Not so loud. Come on, Gaster."

Some of the voices quieted. Sans managed to make out a few words, just barely.

"SSS. OMMMME. TTTHHHHHHHHHH. INNNNGGGGG."

"ISSS."

"CC. OMMMM. INNNNGG."

 _Something is coming._

Sans looked from one shadow to the other, eyelights shrinking.

"What's coming?"

The shadows went silent. Sans looked between them. At times he could almost see faint white shapes in the shadows, almost like faces.

"It's okay. Take your time. Just work with me, yeah? I'm trying to help you."

Something like laughter roared through the shadows. It felt like the entire population of the Underground was laughing at Sans through bad speakers. He resisted the urge to cover his skull; he needed his hands free.

"It's the truth. I need you to help me fix the timeline."

More laughter, louder this time. A thin shadow tried to curl around Sans's ankle, but he brushed it away with a bit of magic.

"Laugh all you want," Sans said mulishly. "Someone has to clean up _your_ mess."

The laughter cut out. Almost like the sound had been switched off.

Sans tried to get a better look at the door through the shadows, but the world out there was starting to dim. There was something familiar about the door, like maybe Sans had seen it in a book before. He certainly hadn't seen it in real life. By now he had explored a good portion of the deep woods beyond Snowdin, always looking for a new place to practice once the previous spot got too torn up. But he had never seen this door. Maybe it was further in than he had ventured.

Or maybe it was just another dream metaphor.

"So," he said after he had given Gaster a minute to think. "Can you tell me what's coming from that door?"

Silence from the shadows, except for their usual hissing of static.

"Well alright. At least we're making progress. We're getting through to each other. That's someth–"

A shadow that Sans hadn't noticed wrapped tightly around his wrist. He froze for a split second and the other shadows leapt at the opportunity. Tendrils and threads of darkness shot forward, wrapping around his limbs, his spine, his ribs.

"Ngh!" Sans tried to push back with his magic, but it was too late. Stupid. He'd let his guard down.

"Stop, Gaster, let me g– _ah!"_

The shadows pulled, tugging his arms and legs outward, making it almost impossible to move. Sans tried to use his left eye but a mass of shadows wrapped around his his skull like a blindfold. He panicked and tried to thrash his way free, but the shadows only tightened their grip.

Something that felt like a hand wrapped around his neck and lifted him easily off the ground, fingers digging into his cervical vertebrae.

 _No, no, nononono…_

He couldn't see, couldn't fight, could barely even breathe.

"THIEF," snarled a voice right next to his head.

"Gaster, please."

 **"THIEF."**

The voice thundered in his skull, and Sans couldn't keep a small, terrified sound from escaping him.

"I-I didn't steal anything."

"LIAR."

The shadows that had looped through his ribs gave a warning tug. Gaster meant to break him into pieces.

"Y-You think I _wanted_ to end up with your magic?" Sans tried to summon some of that magic again, but stopped when he felt a shadow try to reach into his left eye socket. It was like Gaster was trying to dig the magic out of him.

"Gah, stop! Stop! God damn it, you think I _like_ having your magic? Y-You think I'm having a great time worrying I m-might Blaster someone into dust by accident? Hell, you can _have_ it, just let me _go!"_

Soft, broken laughter near his face. There was a clicking sound, and then Sans heard his own voice echoed back at him.

 **"You don't…get to hurt me. Never again."**

More laughter. The shadows tightened, and Sans gasped as his bones ground together. There was another clicking sound, like a tape recorder being rewound, and Gaster played back his own voice this time.

 **"But at the end of the day, you are a failure."**

"S…top. Stop."

Sans couldn't see, but an image pressed into his mind of a grinning, bone-white face.

"BEG."

Sans didn't think it was possible to be so scared and so angry at the same time.

"Fuck you," he spat.

The shadows growled in annoyance.

"GIVE IT BBBBBBACK."

"Would if I could, pal."

"LIAR."

Gaster's hold tightened again and Sans tried to brace himself, certain that something was going to break this time.

 _"That's enough."_

A new voice, speaking from within the shadows. The darkness went silent, startled. The grip on Sans loosened, and Sans didn't waste a second.

He called on every last drop of his magic. Electric blue light exploded forth, bone bullets made of solid light erupting from all directions. In a dream, Sans could have perfect control over his magic–it did exactly as he told it, sweeping outward, wheels of bones slicing through shadow like the insubstantial nothing they really were. Gaster simply couldn't hold on. Something screamed and Sans was released.

He dropped, hit the ground and curled into himself. The light gave one last, implacable sweep, destroying the last tendrils of darkness. Then it faded to a more manageable glow.

Sans hugged his arms and looked up, shaking. He was in a black void. The shadows were gone, and Gaster seemed to have gone with them.

Standing before him was a small, gray figure. It looked like a young lizard monster. It was the most clear, defined thing Sans had ever seen in these dreams, but even so, it still looked wrong. It wasn't just gray–it was washed out, as if the color had been drawn out of it. It had no arms, and its eyes were empty white circles.

 _"Hello,"_ it said. That was the voice that had made Gaster falter.

"Hey." Sans wasn't sure he could handle any more of this, but he put on a shaky smile. "You really saved my skin. Heh."

 _"Heh,"_ said the gray monster. It sounded more like it was echoing the sound than actually amused.

"Who are you?"

 _"I am sorry. Every piece of him is different. Independent. The crueler ones have been focused on you."_

"So I've noticed. But who are you?"

The monster regarded him with its eerie, empty gaze.

 _"You can find me, if you wish."_ It said after awhile. _"In Waterfall. The pier."_

"But who–?"

"SANS! SANS, WAKE UP!"

The void tore itself to pieces as light flooded in, and the gray monster vanished. Sans came awake with a jolt and a shout. Something had him by the shoulders, and he was halfway to summoning a Gaster Blaster when he realized who it was.

He was in his room, in New Home, in the real world, and Papyrus was shaking him gently.

"SANS, IT'S OKAY!" Papyrus was saying, his face full of concern. "It is me, your brother!"

"P…Paps?" Sans squinted at him, disoriented and trying to get his bearings. He let the magic fade before the Blaster could manifest. "What's…?"

"You were having some kind of nightmare!" Papyrus said, not letting go of him. "I heard you from the hallway. Sans, are you alright?"

"Oh." Sans went quiet for a moment, sorting through the dream and trying to imagine what it must have looked like to Papyrus. "Oh, jeez. I'm sorry, bro."

Papyrus pulled back a little, leaving one hand on Sans's shoulder as a sort of anchor.

"Don't apologize! I am simply concerned about you. You were shaking and thrashing and saying things. Though I could not understand them? It almost seemed like another language. Sans, are you…alright? Do you want to talk about it?"

"Nah, no, I'm okay," Sans said, scrubbing at his face. He was covered in sweat. His bones ached, maybe from what Gaster had tried to do to him, or maybe just because he had fallen asleep sitting against his bed.

"Sorry I scared you, bro. It was just a random nightmare. Been kinda stressed lately, guess it just caught up with me."

"Are you sure?" Papyrus didn't look entirely convinced. "What was the nightmare about?"

"It was terrible, bro…the entire Underground…the whole world… _had run out of ketchup."_

Papyrus gave him A Look.

"Seriously?"

"Seriously," Sans said in his gravest voice.

He had a feeling that Papyrus wasn't buying it, but the taller skeleton sighed in exasperation and pulled back.

"I suppose to YOU, that would be QUITE horrifying."

"You have no idea, bro."

"Still! I am glad that you are alright, and that you are awake now. Sans, don't be afraid to tell me if you are stressed or if you have more nightmares like these! I would GLADLY try to help!"

"Heh. I know you would." Sans winked at him and pulled himself slowly to his feet. Of course Papyrus would want to help. That was part of the problem. "But I'm okay. It's more annoying than anything."

"If you say so!" Papyrus stood as well and suddenly frowned at Sans. "Actually, I was surprised to find you here. And sleeping! Didn't you work tonight?"

Sans stared at his brother. Then he looked over to the clock on his nightstand.

8:30 PM. He was a half an hour late.

"Oh no."

How could he have been so stupid?

 _"Damn."_ Sans scrambled to straighten himself out and started digging around in his room. "Damn, damn, where's my phone? Crap, forget it, ugh, I can't believe–"

"Brother, I'm sure it will be alright! If you explain to your boss that you weren't feeling well, I'm SURE he will understand!"

"Hah. Yeah, Paps, sure. Sorry, I'm sorry, I gotta–" Sans pulled the sock off the back of his hoodie and grabbed his bag. "I gotta go, I'll see you later tonight, bye bro–"

Sans was out the door before Papyrus could even answer. As soon as he was out of sight in the hallway, he teleported.

He landed near a convenient bush at the Core's entrance. There were other monsters around, but fortunately no one saw him. He dashed inside, running as fast as he could manage.

He was screwed. He was _so screwed._ All because he couldn't stay awake. All because Gaster had decided to toy with him.

Sans skidded to a stop just inside the puzzle area where he worked. A few monsters looked up, but ignored him when they saw it was just Sans. He speed-walked past them toward the break room so he could dump his bag and hoodie.

A monster with an old-fashioned radio for a head was waiting for him; the overseer of this area.

"Ah. So he decided to grace us with his presence."

The monster's voice came from the radio's speakers, tinny and a bit crackly. His voice was grating even on a good day, but right now it was all Sans could do not to flinch and cover his skull.

"I'm sorry, I wasn't feeling well and then I lost track of time, I would have called but–"

"It's fine. We already pulled someone in off the street to cover for you," the monster said, folding his arms. "That's the beauty of this job, Sand. Anyone can do it."

The overseer never got Sans's name right, which was fine, since Sans had forgotten the overseer's name as soon as he'd learned it.

"I'll stay an extra half hour to make up f–"

"Let me ask you something, Sand. Do you care about this job? At all?"

"Of course I do," Sans said, clutching his hoodie in front of him like it was a security blanket. "Maintaining the Core and its puzzles is important."

"You're right, it is important. That's why we have absolutely no use for monsters who can't be bothered to show up on time."

"It…It won't happen again."

"No, it won't." The overseer waved a dismissive hand. "You can go home, Sand. We don't need you here. You don't have to bother coming in tomorrow, either."

"Come on," Sans said, trying for a winning smile. "I've been doing good work so far, haven't I? It was just one mistake. I'll stay late, I'll–you can keep me an extra hour without pay. Two hours. I won't let it happen again. You don't have to fire me."

"I don't have to, but I want to," the monster said, tilting his head. "You've been doing good work? Please, don't make me laugh. You're practically useless. You can't even reach the tops of some of these puzzles. I haven't even see you use your magic once. Can you even use magic? Don't think I haven't noticed how weak your soul is."

Humiliation burned in Sans's chest.

"Of course I can use magic." He took a breath, trying to steady himself. "I just like doing things manually. All that heavy lifting and stuff. Yanno, just trying to build muscle."

"That's your problem right there," the monster said, prodding Sans in the chest. "That attitude. You think you're better than the rest of us. Better than this job."

"That's actually not true."

"The Core has no use for useless monsters." The overseer pointed at the door. "Out."

"I need this job."

"So does everyone else here. Now, go on." The monster snickered. "Don't make me pick you up and toss you out. It wouldn't even be hard."

He reached toward Sans as if to do just that and Sans jerked backward.

"Don't _touch_ me."

The overseer just laughed. Sans grabbed his bag, turned and walked out. He stormed toward the exit, feeling like he was going to explode.

One of his coworkers, a hulking bull-shaped monster, stepped aside to let him.

"He fired you?"

"Apparently."

"Good."

"Wow."

"Sorry, man," the bull monster said, raising both hands. "I just always was worried I was going to drop something on you and you'd, like, die or something."

"Thanks for the concern."

Once Sans was out the front door and out of sight, he teleported again. He landed in the clearing he'd been practicing in earlier. It was unchanged–the ground still torn up, the stone still sitting placidly right in the center.

Sans dropped his bag and hoodie in the snow and raised both arms.

 _"One–"_

A Gaster Blaster appeared above one hand.

 _"Two–"_

A second, this one over the other hand.

 _"Three–"_

A third, floating above his head.

Sans yelled just to yell. The Blasters went off in perfect unison, three beams of light and magic hitting the stone squarely in the center. The beams kept going, blowing holes through several trees.

The ground shook as one of the trees fell. After a moment, the beams faded and the Gaster Blasters disappeared.

The stone was gone. There wasn't even powder left.

Sans sank into the snow, breathing hard, shaking with exertion and anger. He buried his face in his hands.


	6. The Lost

.

 **ENTROPY**

* * *

Chapter 6: The Lost  


 _Is what you have to do... really worth it?  
_

* * *

Sans wasn't sure why he had thought this was a good idea. **  
**

Papyrus had gotten the sentry job easily, of course. They had stationed him in Waterfall, though they had mentioned that he might be moved in the near future, probably to somewhere near Snowdin. Papyrus had scarcely finished celebrating before he was encouraging Sans to join up as well.

"You would LOVE this job, Sans!" he had exclaimed. "It is mostly SITTING and STARING at things, which you are already EXCELLENT at!"

"I dunno, bro."

Sans really couldn't afford to be picky about jobs, but the problem with the sentry position was the evaluations. Most of that was just standard job interview material, but there was a magic element involved. You had to prove to the evaluator that you knew your way around monster bullets. Sentries weren't expected to do much fighting–-that was what the Royal Guard was for–-but they had to at least be able to hold their own against a threat until help arrived. Sans still had virtually no control over his magic, not even despite daily practice.

Papyrus pestered him for several weeks, and between that and Sans's own desperation, he finally had to break down and sign up for the next evaluation. He'd managed to pay that month's rent only by using the last of his savings and selling a whole lot of his possessions, including most of his science books. The next month's rent was going to be literally impossible if he couldn't get a job in time.

Sans had spent every waking moment practicing his magic to the point of exhaustion. Even so, when the day of the evaluation rolled around, he knew he wasn't ready.

He was standing in one of the Royal Guard outposts in New Home, before an unimpressed-looking dog monster. The monster was holding a clipboard and humming to herself.

This was such a terrible idea. Even if Sans made it to the actual magic part of the evaluation, he was pretty sure he was going to blow a hole in the side of this building. That wouldn't go over well with anyone. He wished Papyrus was here for moral support. His brother was working at his own sentry station, though, and they both knew full well he couldn't afford to take a day off.

Sans just tried to act casual. Fortunately, he was very good at acting casual.

"So, Sans," the dog monster piped up. "You're Papyrus's brother?"

"Yep, that's me."

"He's a good pup. Kid, I mean. Really enthusiastic."

"Heh, yeah. That's Papyrus for you."

"So why do _you_ want to be a sentry?" The dog monster squinted at Sans over her clipboard. "Most people become a sentry because they want to join the Royal Guard someday. Or–-because they're dogs. But you don't seem like either of those."

"Last I checked, I didn't have enough fur to be a dog," Sans said with a grin. "And nah. I'm not Guard material. My bro suggested this job to me, and, uh…I figured, it'd be good to help protect the Underground, what with the humans coming through recently."

"Hm. Fair enough." The dog monster made a few marks on her clipboard. "Alright, well, I've been looking over your Check stats and…mm."

She looked like she was trying to find a way to put it delicately.

"Yeah, uh. I'm pretty weak. I know. Hence, heh, why I'm not Royal Guard material. That and I can't handle that much _royal_ -sponsibility."

She stifled a snort at that, but she still looked concerned.

"Based on the most recent methods for calculating Check stats…" She cocked her head. "It looks like you have 1 HP, 1 ATK and 1 DEF."

"That's pretty much what it was last time I had a Check up."

"The medical report you submitted says you're safe to be out in the field, but…"

"It's true." Sans gave a shrug. He had heard all of this a million times before. "I'm not totally made of glass. Actually, I think I'm mostly made of calcium."

He winked at her, and this time she snorted out loud.

"Alright, then," she said. "Sorry. Just basic stuff I had to go over, you know how it is."

"I understand. Gotta make sure your sentries aren't going to trip over a rock and die, yeah?"

"Pretty much," she said with a doggy grin. "We can move onto the real questions now."

The questions weren't difficult. It was all typical job interview fare, and all that required was the ability to embellish the truth. Sans was very good at that. He breezed through the questions, keeping his hands in his pockets the whole time to avoid fidgeting.

 _Just focus. Stay focused._

After about twenty minutes of questions, forms and trying his best to keep the dog monster amused and liking him, it was finally time for the magic part.

"Pretty simple." The dog led him over to another corner of the barracks and pointed at a target on the wall. The target seemed to feature a badly drawn cartoon cat.

"Just hit the target and you'll be done. I take a few notes, send all of this up the chain and someone will get back to you tomorrow."

"Cool," Sans said, eyeing the target and rubbing his hands together.

Just hit the target. Stay focused. A couple of bones, no Gaster Blasters. The target was about twenty feet away. His aim had gotten better, but reigning in all that power was still his main problem.

The dog monster stepped back, eyes on Sans. He raised a hand toward the target.

Moment of truth.

He called on his magic and held onto it as tightly as he could. It felt like trying to hold a pile of sand without dropping a single grain.

About ten glowing bones materialized and launched toward the target. Most of them struck true; several got stuck halfway into the concrete wall, while the rest left substantial dents.

That was a lot better than he had hoped.

He dropped his arm and his vision went temporarily blurry from the effort of holding back. He rubbed at his forehead and tried to keep from swaying. If he passed out from just a couple of bones, well, that would be that.

"Whoa," he heard the dog monster stay. "You alright?"

"Y-Yeah, I'm fine. Sorry, uh. I've been feeling a bit off lately is all. Magic flu or something."

His vision cleared and he saw the dog monster watching him with a concerned expression, ears slightly raised.

"Well, you hit the target," she said after awhile. "Man. For a little guy, you sure pack a punch."

"Sorry."

"Don't be sorry. It's kind of impressive."

Sans rubbed the back of his skull, not feeling even remotely impressive.

"Anyway, that's that. Like I said, we'll get back to you tomorrow."

"Did I, uh. Do okay?"

"You did just fine," she said with an unassuming smile. He had no idea that dogs could be so good at smiling without giving anything away.

"Well, thanks. Was good to meet you. I look forward to working together."

They shook on it and Sans left, managing not to stagger out the door.

Well. That could have gone a lot worse. Poking holes in the wall was a lot better than blasting the entire building. Or accidentally killing anyone, which had also been in the back of his mind. He wasn't sure if this meant he had gotten the sentry job or not, but it wasn't like there was anything more he could do.

In any case, he had to get home and lie down before he really did collapse.

He teleported, and even that effort was unpleasant. He landed in his room and dropped onto his bed with a heavy sigh. The world spun gently. At least this was progress, one way or another. He had managed to hold back, even if it was only slightly and even if it had almost knocked him flat on his tailbone.

Sans was honestly starting to wonder if he would ever have full control over his magic. Learning to teleport had been very hard, but it hadn't been this hard. Of course, it probably didn't help that Sans found he was stressed all the time. Whether he was practicing his magic, sorting through finances, dealing with Gaster dreams, working with Alphys or just doing nothing at all, there was always _something_ weighing on his mind. Usually several somethings.

He needed a break. Maybe this sentry job would be the break he needed.

Sans drifted off to sleep without even bothering to take off his shoes. He woke several hours later to Papyrus shaking him and shouting his name.

"Ffbbbbww?"

"SANS, WAKE UP!"

"Mm'wake," Sans mumbled. He tried to roll over and ended up sliding off the bed. Papyrus stood over him, hands on his hipbones. Sans peered up at him. Papyrus looked upset.

"Brother, PLEASE tell me you didn't sleep through your sentry interview! I TOLD you to set an alarm! I told you to set TWO ALARMS!"

"What? Oh, that…" Sans sat up, willing his mind to wake up. "Yeah, I–"

"SAAAANS! THIS EVALUATION WAS VERY IMPORTANT! You can't keep SLEEPING through such IMPORTANT THINGS, Brother! I know you weren't very enthusiastic about the sentry job, but I REALLY thought–"

"Whoa, whoa." Sans waved a hand toward Papyrus, using the other to pull himself to his feet. "Calm down, bro. I made the eval. Answered questions, told some jokes, threw some bones around."

Papyrus blinked at him, the fight going out of him all at once.

"Oh."

"I think I did okay, too."

"Oh!" Papyrus grinned. "Well, why didn't you SAY so? That is WONDERFUL NEWS!"

"Yeah, they're gonna call me tomorrow." Sans sat down on his bed and looked away. "I just got tired, so I came home and took a nap, that's all."

"OF COURSE! Of course." Papyrus tapped his fingerbones together, also looking away. "Well, Brother, I am very proud of you! I am CERTAIN you will get the job, and then we can keep ALL FOUR EYESOCKETS out for dangerous humans and evildoers!"

"Yeah, bro." Sans put on a grin. "We'll be awesome."

"ANYWAY! Dinner is just about ready! Come out when you're fully awake and we can REGALE EACH OTHER with the events of our day!"

And with that, he was gone, "nyeh heh heh-ing" his way down the hall. Sans rubbed at his eyesockets to wake up and then draped his hands in his lap. He stared at a point on the floor, unwilling to stand just yet.

Papyrus had been…good about it, mostly. He wasn't angry, and he had let Sans drink all the ketchup he wanted after getting home that night. He never said anything outright, but Sans could tell that Papyrus was disappointed. It wasn't like it was the first time Papyrus had been disappointed in Sans, and if Sans was honest with himself, it probably wouldn't be the last. That didn't stop Sans from feeling absolutely wretched, though. He almost would have preferred it if Papyrus had gotten angry, read him the riot act, because Sans deserved it for jeopardizing the roof over their heads.

Mostly, things had just been awkward between them. Papyrus took care not to even mention the Core, and Sans did his best to do everything Papyrus asked of him, even the mundane stuff. This would blow over, like these things always did. Getting that sentry job would help. And if he did get the job, Sans had an idea for something that would _really_ make it up to Papyrus. It would take time and effort, but it would be worth it.

In the meantime, though, the best thing Sans could do was put on his smile and go join his brother for dinner. Sans got to his feet, made sure his smile was firmly in place, and went.

* * *

Sans had been worried. Not so much because he thought he had bombed the evaluation, but because so much had gone wrong in his life lately that the idea of something going _right_ seemed almost far-fetched.

Papyrus was, naturally, quite a lot more excited about it than Sans was.

"I KNEW YOU COULD DO IT, BROTHER, I KNEW IT!" Papyrus howled as he scooped Sans into a hug and spun him around.

"Whoa, haha, bro, you're making me dizzy."

"THE GREAT PAPYRUS IS JUST SO VERY PROUD OF HIS BROTHER!" Papyrus said, holding Sans up. "You did it, Sans! Now we're BOTH SENTRIES!"

Papyrus was so genuinely happy that Sans couldn't help beaming.

"Well, you know," he said, chuckling. "Couldn't leave you to get all bonely out there in Waterfall by yourself."

"I WILL NOT EVEN DIGNIFY THAT PUN WITH A REACTION!" Papyrus set Sans back down, still grinning. "WHEN DO YOU BEGIN? WHERE IN WATERFALL WILL YOU BE? DO YOU KNOW? DO YOU THINK WE'LL BE CLOSE BY? DID YOU GET TO TALK WITH A REAL ROYAL GUARD ON THE PHONE?"

Sans sat down at the kitchen table, trying to keep up with Papyrus's enthusiasm.

"Tomorrow, near the Waterfall-Snowdin border, and nah, I think it was a receptionist."

"WOWIE! SO SOON! DON'T SIT DOWN, SANS! WE SHOULD GO OUT AND CELEBRATE! It's too bad you're so far away from me but THAT'S FINE! COME ON, SANS! WE CAN GO GET A CAKE FROM MUFFET OR SOMETHING! Preferably the kind WITHOUT spiders!"

Papyrus tugged him back to his feet before Sans could protest.

"Oh, uh." Muffet's pastries were exorbitantly priced. "I dunno. What if we just celebrate at home? I was kinda hoping to stay in today. You know-–last day of freedom before I have to go from 100% lazy to just 98% lazy?"

Papyrus gave him A Look. "I would hope that my influence makes you AT LEAST stay at only 99% laziness."

"Heh, okay. Fair point."

"Not even a SLICE of cake?"

"Ehh. It's all the way on the other side of town, you know?"

Papyrus pouted for a moment, but quickly shook himself out of it.

"ALRIGHT, THEN! If that is what you want, brother! Celebrating at home it is!"

Celebrating turned out to mostly consist of hanging out, watching TV, and on one memorable occasion, playing cards. Papyrus wasn't exactly thrilled at the general lack of actual celebrating, but he got past it soon enough. They hadn't had a nice, quiet day at home in awhile. Sans was just glad for the opportunity to mentally relax.

A job. _Finally._ He just had to hope he didn't screw this one up as well.

Sans made a mental note to get a cake for Papyrus with his first paycheck. One without spiders.

* * *

Sentry work turned out to be…boring. Which was perfect–-exactly what Sans had wanted.

It consisted almost entirely of sitting at a designated station and watching the world go by. You went on short patrols, checked in with your superior, wrote reports on anything worth reporting, greeted any monsters who came by and helped them if they needed directions or the like, and that was pretty much it. Unlike in the Core, no one was watching Sans's every move-–the other sentries stuck to their own stations, and the Guard only came by a few times a day to make sure everything was going well.

It was downright _relaxing._ Once Sans realized that no one would be watching him, he took the opportunity to get other work done while he was at his station. It gave him plenty of time to write notes and equations while he picked apart Betas's notebook. He could even sneak in a nap or two without anyone being the wiser. And during patrols, it was a simple enough thing to pop off to the outskirts of Snowdin and get a few minutes of practice in.

The pay wasn't all that great, but it was certainly better than nothing. After a few weeks, Sans was actually able to start setting money aside again. The landlord even stopped bothering them quite as often.

Spending so much time in Waterfall also gave Sans the chance to explore the piers without anyone asking questions. Waterfall had several piers around the larger ponds, pools and marshes, and that wasn't including the massive bridge that crossed Waterfall's largest lake. Sans initially assumed that "the pier" that the strange, monochrome monster–-Sans was pretty sure it was a him-–in his dream was referencing was that bridge. But there was no sign of him there. Sans checked the piers, but there was no trace at any of them.

Sans was sure the gray monster hadn't been lying to him. Why bother? It was likely that the monster was instead referencing a hidden pier–-or perhaps one that had been erased when the timeline diverged. Sans didn't know Waterfall all that well, and unlike New Home there were a lot of branching caves, all kinds of nooks and crannies. Some areas were known only to Waterfall residents. It was the most poorly mapped area in the Underground, mostly because the whole area was so dark. People would discover a new cave or room in Waterfall about once a year. There was also the massive abyss beneath the garbage dump, which was completely unexplored. It was too dark and dangerous to bother with.

The gray monster could be hiding anywhere in Waterfall, and that was assuming that he was hiding in _this_ Waterfall. For all Sans knew, the monster only existed in his dreams–-perhaps then he was waiting at some imagined pier in Sans's subconscious. Maybe Sans just had to dream the right dream at the right place. He had tried finding the monster again in his Gaster-themed dreams, but the monster had only appeared the once, and Sans had no control over the actual content or scenery in the dreams. All he ever had was the awareness that he was asleep, and on occasion, the ability to wake himself up. In any case, it was enough work just to keep Gaster at bay.

Sans realized pretty quickly that he had no choice but to wait. Wait for the right dream, the right circumstances. The same as usual. Waiting and being patient had become such permanent fixtures in his life that he was starting to get used to it. He had to just accept that all of this–-Gaster, the timeline, the machine, his magic-–wasn't going to be fixed overnight, or even anytime soon. He had understood that objectively up until now, but coming to terms with the fact that he might be stuck in a broken timeline for actual _years_ was different. Frustration and anger would get him nowhere. And they were exhausting, to say the least.

So Sans waited. Weeks passed, then months. He settled into sentry work like it was an old coat. He paid closer attention to Papyrus. He dealt with his Gaster dreams. Eventually Sans moved the time machine into the basement of the old lab and started doing his work and research there instead, where it was less likely for Papyrus to stumble on anything strange. He kept practicing magic out in Snowdin, as far from civilization as he could get. Alphys drew up designs to try and replicate her father's Reset-resistance device. When she wasn't busy with school, the two of them began repairing what parts of the machine could actually be repaired–the hull, some of the wiring, the control panels and so on. And all the while, Sans kept an eye out, literally and metaphorically, for the monochrome monster.

One day, his patience paid off. He had dozed off at his sentry station like usual and slipped immediately into a Gaster dream.

They had never happened during a nap before. Naps typically didn't last long enough, nor was the sleep deep enough. There was probably some biological or psychological reason for that, but those weren't exactly Sans's fields, so he didn't think too hard about it. More than just that, the dream felt different almost right away. Sans fell asleep in Waterfall and woke up in a Waterfall that looked almost identical. The only visual cues that it was a dream were the great swaths of gray in certain areas, as if someone had been painting the landscape and given up part way.

"Seems promising," he said to himself.

He could feel Gaster out there, much further away than usual. Gaster didn't even seem to notice him. There was no shift in the mood, no encroaching darkness to indicate that Gaster's attention was on Sans.

Sans shrugged to himself, got up from the imaginary sentry station, and started walking toward the nearest pier. It wasn't far, maybe three caves away, extending over one of the big marshes. At least walking within a dream never actually felt like exercise. The imagery of the world stayed the same, except that it was much quieter than Waterfall should be. All of the sounds were muted, far off. It wasn't the usual ominous silence of one of these dreams. This felt…peaceful. Perhaps melancholy.

Sans came upon the pier and saw a small figure standing at the end, staring out at the water. He paused at the water's edge. It was him. He'd found him at last.

Sans approached slowly. Even his footsteps on the wooden pier seemed distant. The gray monster didn't move or react. He looked so strange. So out of place. Most of the rest of the world was in color, but this monster was like those patches along the walls and ceiling, where the color drained out. Like something was missing.

He came to a stop a few feet behind the monster, unsure of what to say. The monster spoke before Sans could say a word.

 _"Have you ever thought about a world where everything is exactly the same…except you don't exist?"_

Sans stuffed his hands in his pockets, eyesockets lidding just a little.

"Yeah," he said after a moment. "Once or twice."

It kept him awake some nights. The idea of what would have happened if he hadn't been in the machine when they all entered the darkness. A world without Sans. If he thought about it logically, not much would be different. The only major effect that Sans had on this world was Papyrus. How would Papyrus's life be different if Sans had fallen into the dark and blipped himself out of reality, like Gaster?

 _"Everything functions perfectly without you,"_ the gray monster kid continued. He turned to face Sans. Sans couldn't quite meet his gaze. The monster's eyes were empty, milk-white.

 _"Ha, ha…the thought terrifies me."_

The laugh had no humor to it. There was no emotion there at all.

"I…don't know about 'perfectly,'" Sans said after a long, drawn out moment.

The gray lizard tilted his head.

 _"No. Perhaps not perfectly."_ He paused, almost thoughtfully. _"You can think of the world as a machine. If a small gear falls out, perhaps the cadence of the machine changes. But the change is infinitesimal. The machine must keep moving. And so it does."_

The monster turned away, gaze returning to the dark waters stretching into the distance. This part of Waterfall was very dark, even in a dream. There were no glittering stones in the ceiling, no bioluminescence from mushrooms or glowworms.

"Using that metaphor," Sans said, taking a step closer, "I guess you could say that Gaster almost broke the machine?"

 _"He did break the machine. Then he fixed it. I do not fully understand how."_

"Who are you?"

 _"I don't know."_

"Are you…part of him?"

 _"In a sense."_

"How many parts of him are there?"

 _"Infinite. He is everywhere. Nowhere. It is the same."_

"Oh. Great." Sans heaved a sigh. "So I should be done piecing him together in a few more days then, right? Cool."

 _"It is impossible."_

"I was joking. I knew this was gonna take awhile."

 _"You will not be able to restore the timeline to what it was."_

"Not without his help, no."

 _"You will not be able to restore him, either."_

Sans sat down cross-legged on the pier and folded his hands in his lap. He looked upward toward where the ceiling was lost in shadow. There was a huge arc of colorless gray above them. The more he thought about it, the more it looked like those pieces of the world had simply been…deleted.

"I don't believe that." He said it quietly. "I get through to him every so often."

 _"Yes. With your assistance, he may achieve some degree of…coherence. But it will never truly be him again. What has happened cannot be undone."_

"Why? It's just…some kind of botched Reset. If I can just figure it out–if I can pull enough of him back together, he can help me. I'll fix the machine or build a new one, go back and set all this right."

 _"Set what right, exactly?"_

"Everything, the whole timeline. This is unsustainable, right? Spacetime was fractured. That can't exactly be healthy for the universe. If you break something once, it's easier to break it again. Right?"

 _"Yes."_

"So then…it can't be left like this."

 _"Imagine that you break a vase,"_ the gray monster said, sitting down as well. His tail curled against his side. _"You can gather up every piece and glue it back together. It will be able to hold water and flowers again. But there will always be the cracks and seams. They do not go away. That is how the universe works."_

The monster paused and looked back over his shoulder at Sans.

 _"Entropy always increases, Sans. It is fundamental."_

Sans grinned.

"Yeah, except we have a little thing called time travel. Kinda bypasses all those pesky rules and laws."

 _"You know that is inaccurate."_

Sans looked away, his grin fading. The colorless patches of world were growing, very slowly.

"You're telling me I should just give up."

The monster glanced back at him again.

 _"Didn't he already tell you to, once?"_

"Didn't listen to him then, either." Sans sighed again and nudged a pebble off the pier into the water. It disappeared into the dark with a muffled splash. The water didn't even ripple.

 _"Maybe sometimes it's better to take what's given to you."_ The monster paused, staring eyelessly out into the dark. When he spoke again his voice was softer. _"You still exist, after all."_

Sans shook his head. "I can't give up yet. You…said I can at least pull him together a little."

 _"You will have to. He still has a degree of influence on the world. In the state he is in, he is dangerous. Especially to you. He will keep coming after you, over and over. Eventually you will succumb to him."_

"What…will that entail, exactly?" Sans wished he could take back the words as soon as he said them. He didn't want to know.

 _"He will tear you apart,"_ the monster said without emotion. _"Take every part of you and make it his own. Use you to try and gain better access to the world. He corrupts everything he touches. If you are not careful, he will corrupt you as well. You will become like us. But while his guilt causes him to leave us alone, with you it is his anger that rules. He will hurt you, and you will not be able to die. You will be here, shattered and trapped with him forever."_

Something had tightened across Sans's chest. It was hard to breathe. He looked down and realized that he was hugging himself, so tightly that his ribs were creaking. His soul fluttered against his sternum like a frightened animal.

They were just dreams. Horrible and harrowing, but still just dreams. Or so he had thought. The thought had crossed his mind that whatever Gaster did to him there might carry over into reality, but at the same, it didn't make much sense logically. He had chosen to believe that so long as he could wake up, he would be safe.

So much for that.

"Why is…" Sans's voice came out thin and high, so he stopped and started again. "What did I do to piss him off that much? I didn't _want_ to end up with his magic. I don't even have all of it."

 _"It is not just that. It is…complicated."_ The monster hesitated, as if wondering how best to phrase it. _"He has a lot of emotions tied up with you. Pride, guilt, love, camaraderie, frustration, anger. You were his favorite, after all. It is easier for him to just feel one thing. Anger is simple. If you want to survive this, you must remind him of those other emotions. You were always the only one who could ever stop him, after all."_

Sans was quiet for awhile.

"His 'favorite.'"

The monster said nothing, still staring blankly out into the dark.

"You're…you're Betas, aren't you?"

The monster shifted. He inclined his head just slightly, as if catching a far-off scent. Sans saw his mouth open, but for a few moments, the monster didn't speak.

 _"Ah. That name is familiar."_ The corners of the monster's mouth twitched upward. _"I do not think I am him anymore. But it is nice to hear that name."_

Sans sagged despite himself, drooping against the pier.

"I've missed you," he said quietly. "I'm…I'm so sorry. I should have…listened to you. And that night, I. I never should have called you. If…"

 _"Sans."_ The monster spoke gently. He turned slightly to glance back at Sans. _"I am not really him. Not anymore."_

"But I can get you out of here. If I can just–I can go back and save everyone. You didn't deserve this. No one did. Not even him."

 _"No one ever deserves anything. It is not about deserving. Things happen. The machine is ceaseless."_

"Your daughter misses you."

The monster turned around fully, and something like fear flashed across his face, there and then gone.

 _"Please do not tell her about me."_

"But–"

 _"There is nothing she can do. Telling her about this encounter will do nothing but upset her. She will never see me again. Not even this version of me. It is better if she moves on. Please. Forget about me. Forget about all of this. Stop him from destroying you, and then forget about him. It will be better. You will be happier. Please don't think about this anymore."_

Sans shook his head, squeezing his eyesockets closed. The monster who had once been Dr. Betas was right. It would be easier to forget. He would be happier, he knew that. It wouldn't even be very difficult. The old timeline and Gaster, all of it, Sans could feel it constantly trying to slip away from him. It was meant to be forgotten.

"I can't."

It wasn't just loyalty or sentiment. It wasn't just his desire to go back and fix it, to save everyone. It was…it was too big. Too important. Too personal. His whole life, he had wanted to be a scientist. His whole life, he had wanted to use the _one_ thing he had going for him–-his intelligence–-to try and help people. To see if he could make a difference. To find where he belonged. And he _had_ belonged. Those years with the science division, with Gaster and Betas, they hadn't always been good. Sans had done so many things he regretted, but he had also done things he was proud of. And he had belonged, for the first time in his life. That was never going to happen again. Never. Even if Sans did manage to fix the machine and go back, it would never again be like it was.

He had to hold onto that, both the good and the bad. He had to remember what it was like, what _he_ was like. A time when he had wanted to do good, even though it was hard, even though he failed so many times. If he forgot, then Gaster and Betas and everything that Sans had been were truly lost.

And most of all, forgetting meant forgetting about the power of Save and Reset, about timelines entirely. Gaster had almost obliterated a timeline and reshaped reality to his will. If someone ever tried to do that again, Sans needed to be ready.

He needed to remember.

 _"Very well,"_ the gray monster said with a sigh. _"But please. Do not tell her."_

"Fine. I won't."

The monster nodded. His head shifted again, his gaze landing on a spot on the pier between him and Sans. It was hard to tell if he was actually seeing something, or if he was just staring into space.

 _"How…is she?"_

Sans smiled.

"Alphys? She's good. As smart as ever. Clever. Funny. Dedicated. She'll be graduating soon. She's helping me with the machine. If this works…it means she's helping to save you."

The gray monster was still and silent for a long time. Then, out of nowhere, he smiled. Just a little. Enough.

 _"I am so proud of her."_

"Heh."

There was a rumbling sound, muffled and muted like everything else. Sans looked up. The colors were starting to peel away, and even the colorless swaths were coming undone, leaving white light.

 _"You are waking up."_

Sans got to his feet and dusted off his pants.

"There's so much more I wanted to ask you. Will I see you again?"

The monster was still smiling, but it was sad.

 _"I am always here,"_ he said. _"But you will probably not see me."_

"Just…just like that? But I-"

The rumbling was getting closer, the light creeping in with it.

 _"I tried to leave you a message, but I ran out of time. I will tell it to you now."_

"Betas-–"

 _"To Sans, if you're reading this: good luck. Take care of yourself. Take care of Alphys."_

"I'm going to fix it, okay? I'll get you all out of-"

 _"Time to wake up, Sans."_

Sans woke up.

* * *

Alphys graduated a month later. She had no living family and very few friends who weren't also graduating. Sans and a ghost he didn't recognize were the only ones there to support her. He didn't even have a chance to say hello to the ghost, as it vanished right after the ceremony. That was fine. Sans was here for Alphys, after all.

Alphys came to find him after everything was over, clutching her degree to her chest like it was the most precious thing in the world. Sans had never seen her happier. She almost tackled him with a hug as soon as she spotted him.

"Sans! Thank you so much for coming, thank you!"

"Heh, wouldn't have missed it. Congrats, Al. You're free from the tyranny of classes and professors and grades."

She laughed. "Ha, I know, right? I did it, I really did it, I mean, there were times I r-really thought I was going to just fail completely, but I…" She beamed at him. "I did it."

"I'm really happy for you, Al, seriously."

"I can finally get to work on all the stuff I _really_ want to do! I have all these plans and ideas, I think I-I can start my own lab maybe, just me to start with, but if it takes off, I could get a couple of others involved. I could even–if it did work, we could work together, maybe officially? If y-you were interested?"

"Hey, yeah, maybe. Keep me posted? It'd be…nice to get back into science."

"Of course! Hee hee, you're a huge nerd like me!" She gave him a playful shove in the shoulder and then looked out at the crowds of monsters. Families were hugging their children, graduates were talking excitedly to each other. Everyone was happy.

"I just wish, you know. That my dad could have been here."

"…Yeah. Me too."

"But maybe…m-maybe when I start up this lab idea, maybe we can really get to work on all this. Fix everything, right? Maybe there's…a way to get my dad back."

"Heh. I hope so."

"I wonder if he's proud of me," Alphys said with a sad smile, running her hand over her head spines.

Sans smiled.

"I know he is."


	7. The World Keeps Turning

.

 **ENTROPY**

* * *

Chapter 7: The World Keeps Turning  


Warnings: Chapter contains **body horror** and **medical trauma.**

 _They just showed up one day and... asserted themselves.  
_

* * *

Alphys called Sans one day while he was napping at his sentry station.

"Al? Something up?" She almost never called him during work hours. They talked regularly, but Sans hadn't actually seen her in about a month now. Ever since graduating she had thrown herself into her "secret project," which she had mentioned several times since they had started working together, but never elaborated on. All of her waking hours seemed to have been devoted to this project, whatever it was.

"Hey, uh. Sorry, is this a bad time? Y-You've got that 'just woke up' tone."

"Nah, I was just taking advantage of my union-required break time."

"Okay. Well, I'll be quick...I know um, hehe, how important your work ethic is t-to you. I just wanted to say, uh...heh...I've got a thing happening tonight, and...well, I couldn't get you an invite, cause it's scientists only. O-Or at least, current scientists only, and I didn't know how to explain about you without getting into all that stuff, so-"

"Slow down, Al. Heh. Maybe start over?"

Alphys took a shaky breath on the other end. She sounded nervous, but not her normal brand of nervous. This was something else. There was excitement in her tone usually reserved only for her favorite anime or for scientific breakthroughs in engineering and robotics.

"Okay, yeah, sorry. So, it's kind of like this little conference? I'm gonna be unveiling...something. And some scientists are actually...interested? Like. Like really interested? Like apparently this is a bigger deal than I thought it would be? Like there's g-g-gonna be...um...TV people there? Haha. M-Man. Um so, I guess the bottom line is...uh, if you can...you should definitely watch the news tonight at eight!"

Sans was quiet for a moment, then a slow grin spread across his face.

"You finished it, didn't you? Whatever that secret thing you've been working on is."

"I have! Yeah! It's-it should be really cool, so…"

"Hell yeah. I'll be watching. Sorry I can't be there in person."

"No, no, it's my fault! I should have, um...it a-all kind of happened really fast."

"Well, at least I can support you through the screen. Just imagine you hear me cheering."

"Hehe! I don't think I've ever heard you cheer for anything or, l-like, even be loud at all."

"That's why you gotta imagine it."

Alphys chuckled. Sans glanced up as he heard footsteps approaching. A guardswoman was passing by on her patrol.

"Anyway, I gotta get back to work. Or at least back to sitting around looking like I'm doing work."

"Okay! I'll, um, I'll try to call you after this conference thing. Bye!"

She hung up and Sans hid his phone under his station counter before the guardswoman could spot it. He flashed her a grin, and she returned it with a small wave.

"Hello, sentry. Any news?"

"I saw a Moldsmal. Does that count?"

The guard snorted. "Only if they're wiggling evilly, probably."

"What would an evil wiggle actually look like?"

She chuckled, heading on past his station. "I don't think I want to know. See you."

"See ya."

Sans waited until she was out of sight. Then he sighed, leaned back in his chair and propped his feet up on the counter. He surveyed his domain-the same boring stretch of cave as usual, dotted with echo flowers and water sausages along the creek. It took a lot for Sans to actually get bored, but _boy_ did this job manage it. Sans could take long naps or outright leave his post for up to an hour before anyone noticed. It amounted to hours and hours of sitting and doing nothing, staring at nothing. Sans could only reread Betas's notebook so many times before he memorized it, and after that he could only play so many games of solitaire before he felt like he was going out of his skull. He could have brought books with him, but he'd sold almost his entire collection last year to pay the rent. Every G was going straight into savings. Sans was running out of ways to kill time.

Fortunately, at least today, his shift was almost over. Then he could go home and find out what that call from Alphys had been about. What kind of project warranted media attention? The average monster didn't really care about esoteric scientific advancements, so whatever this was, it had to be big.

Sans decided to finish up his nap in the time he had left. There was nothing else to do, and naps were the only way for him to actually get restful sleep these days. Gaster had been...busy.

He was drifting off when someone shouted his name.

"SANS, WAKE UP YOU LAZYBONES!"

Sans jolted a little and tipped forward. His face hit the counter with a dull _clunk._

"Ow."

"SANS!"

"Yeah, bro, I'm awake," Sans said without lifting his head.

"I CAN'T BELIEVE YOU!" Papyrus said from somewhere close by. "THIS IS THE THIRD TIME YOU'VE BEEN SLEEPING ON THE JOB THIS MONTH!"

Sans picked himself up enough to prop his chin on his hand. He grinned up at Papyrus, who was standing in front of Sans's station with his hands on his hipbones.

"Yeah, well. You know me. I'm so good at sleeping, I could do it with my eyes closed."

"UGGHHHH." Papyrus scrubbed at his face. "Sans, you're going to get in TROUBLE one of these days! What if someone from the Royal Guard catches you?"

"Guards have caught me before," Sans said with a languid shrug. "They don't care. No one cares about the Waterfall stations."

"I CARE!"

"Yeah, but you care about everything. What are you doing all the way out here, anyway?"

Papyrus's whole demeanor shifted abruptly from annoyance to excitement.

"They said I could go home early! I thought I'd stop by and check on you before heading home. I have EXCITING news, brother! I'm being transferred!"

Sans blinked up at him. "That's exciting?"

"YES IT IS! Because I am being transferred to a station near SNOWDIN!"

"Oh, huh." Sans grinned. "Hey, congrats."

Now it made sense. The sentry stations around Snowdin were considered much more important than the ones in Waterfall and Hotland. All of the humans that had come through the Underground so far had come from somewhere near Snowdin. Probably the Ruins, was the general consensus. Sentries positioned at Snowdin would be the first to spot a human, and therefore the stations there were very high-priority. Working there was considered to be just a step below actually being a member of the Royal Guard.

"NYEH HEH HEH!" Papyrus puffed out his chest. "FINALLY, THE GREAT PAPYRUS IS STARTING TO GET THE RECOGNITION HE DESERVES!"

"You're on the up-and-up, bro."

"They're saying that I'm the best and most thorough sentry they've seen in AGES! Because unlike SOME PEOPLE WHO SHALL REMAIN NAMELESS…"

Papyrus gave Sans a very pointed glare. Sans stifled a laugh.

"...I actually fill out proper reports and STAY AWAKE through my whole shift!"

"I keep telling you, you're the only one who fills out those reports."

"And that's why I'M moving up the ladder!"

"Heh. Fair. So you're replacing one of the dogs?"

"APPARENTLY Doggo Sr. is retiring. Doggo Jr. is taking over his area, and I'm taking over Doggo Jr.'s. Tomorrow Doggo Jr. is going to show me around!"

"Well, hey, bro. I'm happy for you. Seriously."

Papyrus beamed. "Thank you, brother!"

"On the downside I guess this means you won't be able to come over and yell at me for falling asleep anymore," Sans said with a wicked grin.

"THAT IS WHAT CELL PHONES ARE FOR, BROTHER!" Papyrus said with an equally wicked grin. "I suppose the commute is going to be longer than usual, but that is nothing that the GREAT PAPYRUS cannot handle!"

Papyrus rubbed his chin, no doubt calculating when exactly he would have to leave in the morning to catch the ferry.

"Heh," Sans said and paused. Now was as good a time as any.

"That reminds me. Bro, what would you think about...like, if you had to live somewhere other than New Home, would you be okay with Snowdin?"

Papyrus frowned, looking taken aback.

"Are we in trouble with the landlord again?"

"Heh, when are we not? But nah, this is more hypothetical. Remember we talked about maybe moving awhile ago? If you had to pick some other place to live…"

The apartment had become suffocating over the past year. Too many memories, too many bad nights. Sans could barely stand to be in his own room anymore. And Sans hadn't told Papyrus, but the landlord had increased the rent in the last few months. He was actively trying to drive them out, and Sans was sick of it. He was sick of the whole neighborhood, of all of New Home.

If Papyrus wanted to stay, though, Sans would just deal with it.

Papyrus looked thoughtful.

"Well, I DO like Snowdin! The snow is nice. I've NEVER built a snowman before! And now that I'll be working there, it'll be much easier to also live there. Waterfall is okay too, I suppose. It's VERY damp. You know what, brother? So long as it's not Hotland, I think I would be alright with living anywhere!"

Sans chuckled. "You _really_ hate Hotland, don't you."

"Hotland is GROSS and TERRIBLE! What about somewhere else in New Home?"

"That's an option too."

"HMMMMM! What a difficult decision! I think if I could choose ANYWHERE IN THE WHOLE UNDERGROUND...I think I'd choose Snowdin!"

"Okay. Cool."

Sans grinned. He had a plan, and with Papyrus's new job, now was the perfect time to move on it. Now before anything else happened or the landlord decided to raise the rent again.

"Sans...everything is okay, right?"

"Everything's great, bro, really." He gave Papyrus a lazy thumbs-up. "Better than great. Why don't you head on home? Enjoy your couple extra hours of freedom. I'll see you tonight."

"ALRIGHT BROTHER," Papyrus said, apparently convinced. "I shall see you then! AND DON'T FALL ASLEEP ANYMORE!"

"I make no promises," Sans said with a wink.

Papyrus made an aggravated noise, spun on his heel and was off.

Sans propped his elbows on the counter and smiled to himself. This was nice. Something was actually going right.

He spent the last few hours of his shift napping, making some calls and arranging a few things. The plan would probably take a couple more weeks if not a month or two, and Sans was hoping he could keep it a secret for that long. He wanted this to be a surprise. Something nice for Papyrus to make up for the chaos of the last year.

He was also quietly hoping that Papyrus hadn't just been humoring him.

Finally, Sans closed up shop and teleported home. He was just in time for the evening news. Papyrus called a greeting from the kitchen, then went back to humming and cooking something that smelled like burnt cardboard.

The news was the usual fare at first-reports from the Core, updates on what King Asgore was up to, traffic reports, the latest in crime (some Icecaps had stolen each other's hats and caused a short-lived feud). Sans was about ready to nod off when the newscaster finally said something interesting.

"And now, our top story this evening-robots!"

This had to be it. Sans made himself wake back up and pay attention. Of course it would be robots. He wondered what Alphys had built.

"We now take you live to the University of the Underground, where scientists are about to unveil a robot they say will change the world...forever!"

"SANS, DID I HEAR SOMETHING ABOUT ROBOTS?"

"Yeah. Maybe they built a giant one that's gonna punch the mountain in half. Heh."

The scene showed a lecture hall at the university, one Sans recognized. Alphys was up on stage, looking incredibly pale, surrounded by other people who had to be scientists and professors. The lecture hall was buzzing with noise. It had to be almost full.

One of the professors patted Alphys's shoulder, smiling faintly. She took a deep breath and stepped up to the podium.

"Um…"

There was a whine of feedback from the microphone. Alphys squeaked a little and leaned back.

"S-Sorry." She cleared her throat. "I...I would like to present t-to you all...my life's, uh, work. A living robot. A…" She glanced at the scientists around her as if uncertain. "A robot with a soul."

The lecture hall went dead quiet. Sans leaned forward on the couch.

Alphys turned and extended a hand toward a curtain at the back of the stage.

"His name is Mettaton."

A metal hand swept the curtain aside and a robot appeared.

Sans wasn't sure what he'd been expecting, but a rectangle with two arms and a single wheel was not it.

"Thaaaaaat's right, ladies and gentlemen!" The robot yelled in an appropriately robotic voice. He spread his arms wide and rolled up next to Alphys. "A robot with a soul, the ultimate achievement in robotic engineering! Our own Dr. Alphys has done it! Isn't she great?"

The robot named Mettaton slung an arm around Alphys and hugged her tightly. Alphys looked poleaxed.

"Always knew she could do it! Let's all give her a big hand!"

Mettaton started clapping and the word APPLAUSE scrolled across the screen on his front. A few monsters tentatively joined in.

"Wowie!" Papyrus appeared from the kitchen with a plate of something black. "What a COOL robot!"

"Yeah…" Sans said, barely noticing as Papyrus sat down beside him.

"Now, I'm sure everyone has an _awful_ lot of questions for our dear Dr. Alphys and for yours truly. No, no, don't tell me! 'Mettaton, what are you going to do now that you're alive and here and looking _so very_ good?' Why...I am here for _you,_ my fellow monsters! I am here to bring a bit of light into this dark, grim, nasty place we all live in! What the Underground needs more than anything is an _entertainer!_ And that's what I'm here for! Dr. Alphys here-"

Mettaton patted Alphys's shoulder. Alphys flinched and forced herself to grin.

"-has programed me with all the very best! Acting! Singing! Reporting! _Drama!"_

Mettaton pressed the back of his hand to the top of his rectangular body and feigned a swoon.

"Finally, the Underground has the star it _truly_ deserves. I'm excited to be here with you, Underground. I can't _wait_ to bring a little light and joy into each and every one of your lives!"

Mettaton bowed to the best of his ability. There was another round of applause, this time louder and more genuine, without the robot needing to flash the word. He clearly knew how to play a crowd.

The announcement apparently over, reporters rushed in to shove microphones toward Alphys and Mettaton, clammoring for attention. The scientists on stage were also talking animatedly amongst themselves, occasionally pointing toward Mettaton and Alphys. Everything past that was mostly noise.

"He is VERY charismatic!" Papyrus said. "I like him! And he is RIGHT-the Underground really DOES need an entertainer! Humans have those...what are they called? CELEBRITIES! AHA, YES! It seems the GREAT PAPYRUS will have a fellow STAR to shine alongside him!"

"...Yeah," Sans said after a moment, remembering that he was supposed to...say something. Anything. He grinned up at Papyrus. "Though he's definitely not as great as you. Heh. It's not even a competition."

"OF COURSE! NYEH HEH!"

Sans stared at the television, though there was nothing new aside from excited reporters and Mettaton's hammy responses. Alphys practically vanished into the background behind the other monsters.

A robot. A robot with a soul. Alphys had created a _robot with a soul._

He knew she was brilliant, but this was on an entirely different level. She had done what Sans, Gaster and Betas had assumed was impossible-she had created an _artificial soul._

Why hadn't she told him? Clearly she had wanted to keep it a secret, had wanted to surprise the entire Underground. But she had to know what this meant-she _had_ to know what this could mean for Sans, for both of them. If she had created one artificial soul, she could create more. She could create enough to power the machine.

They could have an endless supply of artificial, bodiless souls. There would be no limit to what the machine could do.

It was a little confounding. She had created an artificial soul and had decided to put it in a robot meant for...entertainment? It seemed so superficial. It seemed almost unlike Alphys entirely. Or then again, maybe this whole "celebrity robot" thing was actually genuine. Mettaton had a point-life in the Underground was rather dry and colorless. All the best media and entertainment came from the Surface, and even then it wasn't like monsters always had the best frame of reference for what passed as entertaining to a human. Enjoying human media required a bit of research, which wasn't necssarily very fun. The idea of having a source of entertainment here, underground, designed specifically for monsters...it could bring a lot of joy and hope to people who very desperately needed it.

It made sense for Alphys to come up with something so odd and yet so nuanced.

Still. That soul. Sans stared at Mettaton, still front and center on the screen.

Sans had to talk to Alphys as soon as he could.

* * *

The following day, Sans tried calling Alphys. No answer. He tried again three more times over the day, but she never picked up. That was fine. Alphys probably didn't exactly _like_ the limelight, but if anyone deserved some recognition, it was her. The whole Underground now knew how brilliant she was. Even the average monster understood that it was, until now, _impossible_ to create an artificial soul.

It made sense that she would be busy.

Sans tried the next day. And then the day after that. She picked up that evening and started talking before Sans could say a word.

"S-Sans, I'm so sorry, I know you've been calling me but I've been _so incredibly busy,_ so many things are happening a-and I really want to talk to you but I-I just have no time, everything's so...haha it's just crazy. I'm sorry, I h-have to go but I promise I'll call you in a day or, or maybe two, I'm sorry!"

"W-"

She hung up. Sans put his phone down with a sigh.

He stopped calling her and settled into the idea that he would have to wait. Not like that was anything unusual. Another day went by, and another. He saw Alphys on TV one more time. Mettaton, on the other hand, seemed to be the only thing on TV at all. According to Papyrus, Mettaton already had at least one show going. It was, as Papyrus put it, "THE BEST SHOW ON TELEVISION EVER!" Sans wasn't too sure what the show was actually _about,_ despite watching it once or twice.

Sans could only handle Mettaton in very small doses. The robot was dynamic and completely insufferable, but in a sort of endearing way.

The effect Mettaton had on the Underground was immediate. He and his show were all anyone could talk about. It seemed like everyone who came by the sentry station had to comment on Mettaton, on the latest gossip or what had happened on the latest episode of his show. Sans found it all rather baffling, but it was nice to see monsters actually excited about something.

A week went by. Sans sat on his thumbs.

Halfway into week two, Alphys finally called him.

"H-Hey. It's me. I-I'm really sorry this took so long. It's been-hah. It's been nuts."

"Nah, don't worry about it. I understand. You're kind of a celebrity now, huh? Bet you haven't gotten a decent night's rest in days."

"Haha, sleep? What's that?" Alphys chuckled. "No, but...I'm not the celebrity. That's deeefinitely Mettaton."

"Well, you created him. Everyone knows your name now. Must be…kind of overwhelming."

"Heh. You have no idea."

Sans leaned back in his chair at his sentry station, hoping none of the guards decided to show up. The vast majority of them were very lax about what the sentries got up to, but Sans didn't really want a lecture right now if he could help it.

"Are you free now? Can we talk?"

"Um, yeah, I was hoping to see you actually. A-Are you at work?"

"Yeah. I could probably get away, but-"

"No, no, it's fine, I, um, it's all quiet right now and, m-man, I've really missed quiet! Um. But I'll be around this evening? You think you could swing by?"

"Sure. You wanna get coffee or something?"

 _"Nooooo…"_ Alphys wailed gently. "I've been r-running around getting coffee with people and doing interviews and answering questions and showing people my r-research notes and signing stuff and m-meeting with...r-really...important...people? Th-The point is, I've been out of my apartment for, like, it feels like a billion years. I-I really just want to stay in right now. I-Is that okay? I-I'm sorry, I hope that didn't sound rude or anything…"

Sans laughed a little. "Nah, Al, it sounded more _bone tired_ than anything. I probably would have collapsed days ago if I were you."

That got the laugh he was hoping for.

"I'll come by this evening and we can chat."

Sans napped through most of the rest of his shift, catching up on some much-needed sleep. Last night had been a Gaster night, and the nonexistent doctor was as intense as ever. Gaster was clearly frustrated over how long it was taking to break Sans.

Sans hadn't forgotten the gray monster's warnings. He couldn't let his guard down when he slept, not for a second. Gaster hadn't become any less persistent over time.

No one bothered Sans through his nap, either, not even Papyrus. It was strange to see so little of his brother so suddenly. Papyrus left in the morning before Sans did, so the only time they saw each other lately was in the evening. At least Papyrus was enjoying his position in Snowdin. If Sans was feeling a little...lonely, then that was his own problem. Sans had no intention of ruining this for his brother.

Eventually Sans packed up his station and teleported to Alphys's apartment. He knocked on her door. For a few long moments, there was no answer-then he heard her voice from within.

"Sans?"

"Yeah."

"Come on in, it's open."

Sans went in and found the apartment dimly lit. It was much tidier than normal; Alphys had likely been forced into one or two panicked emergency cleaning sessions during the last week and a half. Alphys herself was in her living room, sprawled on her couch and watching Mew Mew Kissy Cutie. She muted the sound when he walked in and gave him a vague wave.

"Man," he said, looking her over. "I thought you _sounded_ tired, but you literally do look like you haven't slept in a week."

"God." She scrubbed at her face. "I think I-I've maybe slept a total of...two hours? Since the conference. I think I've talked to half the monsters in the Underground."

"Heh. Well, everyone's real excited." Sans took a seat at the other end of her couch. She scooted her feet down to give him more room. "Mettaton is really blowing up."

"Would you believe it if I told you that I kind of...I kind of had no idea this whole thing w-would end up being this big? It was just kind of...a, um...a pet project."

"You created a robot with a _soul._ That's not just big, it's huge."

Alphys gave a nervous chuckle and curled her tail over her legs. She was staring at the TV, not at Sans.

"Y-Yeah. I...um, I guess I did."

"Al, how come you didn't tell me?" Sans tilted his head at her. "I mean, an artificial soul? I had no idea you were working on something like that. Can you replicate it? Because if you can...I mean, that's the answer right there. That's how we get the machine working again."

"Oh." Alphys covered her face briefly. "Oh, jeez. No, no, it's not like that. It wouldn't work. It's-uh-it's not really-it's not like a monster soul or a human soul. I-I'm sorry I didn't tell you, it was...k-kind of a...secret? And I didn't even r-really know what I was doing. I didn't...heh, I didn't think a-any of this would work, really."

Sans frowned. "So he, what, he doesn't actually have a soul?"

"No, he does. He definitely does. It's just not-um. It's not really-literally a soul? I guess? It's complicated. It's-haha, you know, it's engineering stuff! Really complicated. Yeah. It's-imagine if you could make a soul o-out of...machinery and circuitry and monster magic. It-I mean, if you do it right, I guess-you end up with an actual soul. A soul enough to make a machine come alive and think and feel. But it's not, um...it's not like, really, a physical thing like a human or monster soul, it's-it's a machine's soul! So it's...it's like ninety percent code and stuff like that. I-I'm sorry I'm not better at explaining it, it's just, you know, it's engineering stuff, it's, it's computers and...and software and...and all that junk. So y-you can't use something like that to power your machine. I'm sorry if it got your hopes up, Sans, I'm really-I-I never intended any of this, really. If you were going to use souls to power that machine, it would _have_ to be human souls. Even monster souls wouldn't work. K-Kind of like the barrier, in that sense."

Sans was quiet, leaning back in the couch, watching Alphys talk. He hadn't gotten his hopes up, not really. Of course not. That sinking feeling in his ribs had to just be something else.

It made sense. You couldn't artificially create a soul-it was like trying to artificially create life. People had tried in the past, even people who weren't Gaster-monsters and humans alike. You could come close, but anything you created would merely be an approximation, the next best thing to the genuine article.

And yet...something still didn't seem quite right. Alphys was more nervous than usual. Her explanation sounded legitimate, but Sans got the distinct impression that she was trying to hide something from him.

Strange.

"Alright," he said after awhile, shrugging to himself. "Guess I was jumping to conclusions. Still-even if it's not exactly like a monster soul, it's a pretty incredible achievement."

"Yeah." Alphys rested her head on her arm and closed her eyes for a moment. "Everyone sure seems to think so."

"You don't sound too happy."

"I just. I dunno, I'm sorry. I guess I'm just...tired? It's all been really overwhelming. I'm not used to having people...c-compliment me or...or think I've actually done something...worthwhile? It...just feels like...I dunno. Like I didn't really earn it…"

He gave her a patient smile.

"Al, you've been working on this thing for how long? Of course you earned it."

She buried her face in her arm and made a muffled sound. Sans reached over and patted her foot. It made sense, he supposed. It was overwhelming to suddenly have the world focused on you. And for someone with the sort of self-esteem issues that Alphys had, it would be pretty easy to tear oneself down and assume all your achivements were unearned or not a big deal.

Sans understood. He was a bit like that as well.

"You'll probably get used to it pretty soon."

"I guess I'll have to," Alphys said, lifting her head enough that she was no longer muffled. She looked away from the television, staring at Sans with an almost nervous look.

"Can I...tell you something, if you promise to keep it a secret?"

"I'm not too good at promises, but sure."

"You _really_ can't tell anyone about this, though. Not yet. It's-It's big. Th-There's gonna be an official announcement sometime soon. But I just-I really want to tell someone."

She looked like she was trying very hard to hide a smile.

"...Sure, Al. I won't tell anyone."

"Okay. So." She took a deep breath and pulled herself up into a sort of sitting position. She drew her knees up to her chest and turned to face him on the couch, tail draped over her feet.

"So, everyone has noticed Mettaton. The whole Underground. I-It's like you said. Even if I don't... _feel_ like it's a big deal, it still _is._ It's...huge. And. Well. A lot of important people have been talking to me. In...Including, um. K. King Asgore."

Sans blinked at her.

"Whoa."

"I know!" She threw her arms up. "It's crazy! Oh, man, Sans, you should have seen me. He, he summoned me to the palace and...and I'm just standing there _freaking out_ because it's _the king_ and I'm s-s-standing in his _throne room_ and I'm just, just casually having a heart attack while I wait for him to show up-and then he walks in and-"

She clutched at her face, blushing fiercely.

"Ohmygosh, he's so _handsome_ up close! I had no idea! I mean, I've only seen pictures or seen him from a distance, and I always thought, wow, he's a good-looking monster, but _up close,_ oh man, I made such a fool of myself, I was just standing there staring because he's _so_ big and fluffy and handsome _ahhh I'm such trash."_

Sans couldn't help laughing a little.

"Sounds like he really got your _goat."_

"Sans, oh my God!"

She thwapped his side with her tail, but that just made him laugh harder.

"Shush, you-punny bone monster! I-I'm trying to tell you something important!"

"Okay, okay, I'm sorry, continue."

"Anyway." Alphys took another deep breath, still blushing. "I could barely pay attention to what he was saying, I was so flustered. But then he says something and-and I kind of froze up and-and then everything happened really fast after that."

She fell silent, clutching her face and at a spot on the couch cushions. Sans waited, but she didn't continue.

"...So? What did he say?"

"He." She looked up at Sans again. "S-Sans, he wants me to be the new Royal Scientist."

Sans went still. For a minute, neither of them spoke.

"That's…" A smile spread slowly across his face. "Al, that's _amazing._ Dude, congratulations!"

"It is amazing!" she said, grinning nervously. "But it's also really _not_ amazing! I-I don't deserve to be the Royal Scientist! All I did was make a robot!"

"A robot with a soul. And a personality almost as big as my brother's, which is saying something."

"Yeah, but-but I didn't really _mean_ to do that! And-it shouldn't be me. I-I'm a mess, I'll just mess it up, I know I will. It's so much responsibility. It should be _you."_

"Pfft."

"I'm serious! You-you actually _worked_ with Doctor G...Ga...whatever his name was."

"Gaster."

"Right, yeah. It's...so easy to forget. You actually worked with him. I-I tried to tell King Asgore he had the wrong monster, but...instead I just...said yes."

"Al, I'd make a terrible Royal Scientist, trust me. I can barely manage to be a sentry. But you, you'll do great. You'll be able to accomplish so much."

"It's just so much responsibility...it's...so much is changing so fast." Alphys rubbed at her face, looking exhausted again. "Everyone's gonna look to me to lead the scientific community. What if I mess it up? I just d-don't think I'm cut out for this."

"Al, you'll do great. And hell, if you ever need help, I'm always here."

"That...does mean a lot to me, Sans. Thank you." She ducked her head. "I'm just so tired and overwhelmed. And, heh, Mettaton isn't making it easy either. He's pretty needy. He already wants me to make updates to his body. I...guess if I'm the Royal Scientist...I'll have access to all kinds of resources. I'll be able to give him the body he _really_ wants. I just...I'm really worried. It's one thing to f-fail on your own, but it's so much worse to fail when everyone's watching."

Sans smiled reassuringly.

"It's gotta be a lot of pressure," he admitted. "But I think you'll be okay. Just...be careful, and take things slowly. Don't try to accomplish everything all at once. No one can tell the Royal Scientist what to work on or how fast to work."

"Except for Asgore," she pointed out. "And p-public opinion."

He waved his hand. "Nah. You have to set your own pace. If you try to rush it, try to appease everyone, or…"

He trailed off for a moment and rubbed the back of his neck.

"Just...so long as you take things slow and don't cave under the pressure, you'll be fine. And...think before you do anything. Don't get…" He smiled faintly. "Don't get desperate."

Alphys watched him for a moment, concern in her features.

"He got desperate, didn't he? That's...why everything went wrong, right?"

"Yeah. Pretty much."

She sighed, gaze settling on her knees, eyes closing halfway.

"Still...it's big shoes to fill. And I don't even _wear_ shoes."

"I believe in you, Al. You'll do fine."

She smiled without lifting her head.

"You're a really good friend, Sans."

"Heh. Same to you."

"Maybe Asgore will let me work with the human souls someday. Then maybe...we could really fix the machine. Well, haha, then I guess if it all went right, I wouldn't be the Royal Scientist anymore."

"Nah." Sans shook his head. "If it all _did_ go right, I wouldn't let him within five feet of a Bunsen burner ever again. He's done. One way or another."

Alphys studied Sans for a moment, though Sans was looking away. He couldn't see her expression.

"You know, sometimes I wonder if…" She shook her head as he turned to look at her. "Never mind. You know, they're going to set me up in that old laboratory in Hotland. That's where the science division used to be, right? They're gonna renovate the whole place."

"Oh. Thanks for the heads up. I'd better move the machine somewhere else. It's still in the basement over there."

"Yeah, heh. Wouldn't want them stumbling on that. Ugh. Anyway...I guess I should try to get some sleep for real. Gonna...gonna have a pretty wild life ahead of me, huh?"

"Heh, that's for sure. But you'll be okay."

"Thanks for talking to me, Sans. It really helped calm me down. Maybe...maybe it'll all go alright."

* * *

Sans dreamed of Gaster that night.

He found himself in an endless black void. The exact same darkness that had once lain beneath the Core, churning, demanding.

Sans sighed and sat down in the dark. Gaster was as intense as ever these days, but he was losing his creativity when it came to dream landscapes. Even this void didn't scare Sans as much as it used to.

"Two in a row? You must be pissed about something."

Sans had a good idea as to what it was, though he was never quite sure just how much of the real world Gaster was able to see. From what Sans had pieced together over the last year, Gaster's perception of the world-and of time and space in general-was as shattered as he himself was. A year ago, Gaster had tried to warn Sans that _something_ was coming. He had warned him of the same thing twice since then, though he never managed to clarify what the something was, or when it was coming. Sans took that to mean that Gaster was seeing something in the future, and that in Gaster's shattered state, he was unable to make sense of it. If Gaster was technically everywhere, then that meant he was also seeing everything, at every point in time. It was pretty standard quantum physics, really.

Sure enough, he appeared not long after Sans's comment, or at least his avatar did. Tonight he was taking the form of Alphys-so that answered that question. Her entire head was obscured by glitching static, but Sans could tell it was her.

"The world keeps turning, Doc," Sans said, leaning back on his hands. He was too tired for this. Two nights in a row. Gaster had never done that before.

"We're getting further and further away from how things were. It's leaving you behind." Sans chuckled. "Maybe it's leaving me behind, too."

A whole year now. Over a year. Sans wasn't even sure when the anniversary had been. It wasn't exactly a day he liked to remember, after all.

Alphys took a step forward. Sans didn't move, staring up into the static of her face. He could hear it, as always-rushing, hissing. Almost like distant water.

"Yeah, I know," he said. "Same old, same old. You try to break me, I don't let you, around we go. You must be furious. Being replaced-unable to do a thing about it."

The hissing of the static increased in volume and the void churned around Sans. He winced a little.

"I know. Shh. Hey. Why don't you sit down? Not that you can sit, or...anything at all, really. I know. But just. I'm tired, Doc. You must be tired too. How long are we gonna keep this up?"

Alphys-not-Alphys seemed to regard him for a few moments, face crackling. Sans watched her-him-carefully. Gaster liked to try to get the drop on him, catch him off-guard while his focus was elsewhere. There were probably shadows aiming for his back this very moment.

To Sans's surprise, Gaster sat down.

"Yeah. Sitting is nice, right? Always did like-"

True to form, the scene changed. Light poured into the void, making Sans flinch and squeeze his eyesockets shut. There was a rush of discordant noise and Sans felt the dreamscape shift, felt a room come into existence, heard the noise settle into comprehendable sounds. The sounds weren't pleasant-distant moans of pain, muttered words, the beep and hum of medical equipment. Sans smelled disinfectant.

"Oh boy."

He opened his eyesockets and found himself strapped to some kind of operating table. A bright light hovered above him, making his eyesockets hurt. Next to him was a medical tray, decorated with surgical tools. They glinted in the harsh light.

Sans sighed heavily.

"This one again? Didn't we do this one last month? Listen, bud, if you're just gonna break my bones again I'm gonna _bore_ myself awake."

He gave a cursory attempt to move, but it was no use. He couldn't even turn his head. His eyelights took in the whole room. It was a pretty solid depiction of a medical room, but one of the walls bent slightly to the side. In a far corner was a patch of darkness, where Alphys was still sitting, her face still obscured with static.

"Doc, it's been a year now. Can't we just-?"

There were footsteps approaching. Sans's eyelights slid in the opposite direction to see another Alphys walking slowly toward him from an open door. This one looked more genuine, though her glasses were bright and opaque, hiding her eyes. Sans had never seen Alphys look so blank.

"Alright. Two Als. Kinda liz- _hard_ to see where you're going with-"

"YOU THINK. SHE. WILL REPLACE ME?"

Gaster's voice came from the Alphys in the corner, his voice popping with white noise. He had gotten slightly better at communicating over the past year, but he wasn't quite there yet.

Sans looked at the Alphys standing over him.

"She already has. She'll do a lot better than you."

"This has to work," Alphys said in her own voice, glasses glinting. "I-It has to work this time. I just have to keep up the dosage and...a-and it has to work. I can't fail again."

She was holding a syringe filled with red liquid. Red...red...why was that significant?

Sans squirmed against the bindings.

"SHE. WILL MAKE. ALL THE SAME. MISTAKES."

"She's better than you," Sans said, eyesockets widening as Alphys raised the syringe. The needle was long and wide, the kind usually used for extracting bone marrow.

"She's-she's better than you. She's-Al, hey." It was stupid, it wasn't real, she wasn't real, there was no point in talking to her, but Sans couldn't stop staring at that needle. "Al, you know I'll help you, right? You just-have to talk to me. I'd never let you go down the same path he did."

"IT IS TOO LATE. HAS HAPPENED. HAPPENING. WILL HAPPEN."

"I-I know you're scared," Alphys said, voice wavering. "But this is the only way to save you. This-this might hurt."

"THIS WILL HURT," Gaster said, almost in a singsong.

"Try to hold still."

Alphys lay a hand on his hip, claws gripping the upward curve of the ilium.

Sans squeezed his eyesockets shut.

"Okay." He tried to breathe. "Okay. Okay. It's a dream, you're fine, you're fine, you're fine…"

He repeated it like a chant until he felt the needle go in.

Sans screamed.

His hands balled into fists, his toes curled, his left eyesocket snapped open and came alight, yellow-blue light spilling into the surgery room. _Nothing_ could have prepared him for pain like this, the relentless pressure of the needle, the sudden flood of something bright and sharp and searing and _red_ coursing through each of his bones.

Red. Now he remembered.

"DETERMINATION," Gaster said from close by.

That was enough. This was too much. Sans called up his magic, tried to shape it. He just needed to get off this table, maybe punch Gaster in his nonexistent face and then make himself wake up. If he could just wake up, this would be over.

The magic came, but it was all wrong. Red overtook the electric blue, bled into the yellow. Red sparks jumped from his bones. Sans gave a sharp cry as his magic failed entirely, spilling uselessly into the room as uncontrolled sparks and flashes of light. His left eyesocket went red, and Sans felt something liquid pour out of it.

"Gaster, _stop!_ Stop, it's a dream, it won't change anything!"

The lights in the room went out. Alphys vanished, most of the room faded into darkness, lit only by reddish light. He could still feel it roaring through his bones, trying desperately to escape. A new sensation came over him-not painful, but doubly horrifying. He looked down at himself to see that some of his bones were starting to melt.

"Please-"

Something unseen seized his jaw, forced his head upward.

"IN ANOTHER LIFE. I DID THIS TO YOU."

Glowing white hands appeared in the dim light, each holding a syringe.

"ONE INJECTION AT. A TIME. UNTIL YOU WERE. PERFECT. UNTIL YOUR BONES. SHIFTED INTO. SOMETHING ELSE. MY WEAPON. MY SCIENCE PROJECT."

Sans couldn't feel his legs anymore, only a mass of viscous liquid where his legs should have been. He closed his eyesockets again. He wouldn't look at it. Feeling it was bad enough.

"Not this life."

"IN ANOTHER LIFE. I CREATED YOU. CARVED FROM. PIECES OF MYSELF. YOU. YOUR WORTHLESS BROTHER. KEPT YOU HIDDEN. HURT YOU JUST. TO SEE. IF I COULD."

"Ghhh _hhh,_ not _this_ life."

"IN SO MANY LIVES. I HAVE BROKEN YOU." Gaster's voice dropped to almost a whisper. "OVER. AND OVER. AND OVER. AND OVER."

 _"Not. This. Life."_

He couldn't feel anything anymore. He tried to call on his magic, but only red came out, sparking painfully.

"IN THIS LIFE-"

 _"Fuck's sake, shut up!"_

Sans couldn't tell where he ended and the darkness began, where _Gaster_ began. Gaster was trying to overtake him.

"Shut up, god, just shut _up!_ I stopped you. I stopped you over and over and _over and over."_

Gaster said nothing. Sans grit his teeth, only they weren't really teeth anymore.

"I'm so done with this," Sans snarled. "A whole goddamn year and you still can't get past all that stupid anger. You know, I've. I've actually been delicate up till now. Been-been trying to give you the benefit of the doubt. But nah. I'm done."

Gaster almost seemed to withdraw slightly, but Sans didn't let him. He couldn't move-didn't really have a body left _to_ move-but he pressed out with his mind, the false Determination, grabbed onto Gaster and didn't let go.

"Your science project," Sans spat. "Yeah, sure, I bet there's a billion timelines out there where that's the case. I bet there's timelines where you won, that night on the catwalk. Destroyed the whole world, brought us both back to the beginning. Turned me into whatever you wanted. Sure. You can be _real proud of yourself._ All those Gasters out there who succeeded! But you know what? This life? This timeline? _I_ won. For once in my goddamn life, _I fucking won._ Broke down and cried like a stupid baby and got you to _hesitate._ Or did you _forget_ that part in all this-this bullshit trying to break me, trying to do whatever that poor guy who isn't Betas told me you were going to do? Do you remember him, too? Do you remember how _goddamn horrified_ you were when you realized he was going to die because of us? Cause I saw the look on your face as we were all falling, Gaster. I don't remember everything from the old timeline, but I rememember every _second_ of that night. You _hesitated._ You _stopped._ You got scared, you got horrified. The very last thing you did was save my worthless damn life. No, hell. The _very_ last thing you did was put a broken timeline back together, patch it all up with duct tape, because you _knew_ you'd done wrong."

Gaster cringed, wilted. Sans gripped tighter.

"S...SAVE…"

"Yeah, that's right, asshole. You saved me. You saved a timeline. A timeline _you_ broke in the first place. You know what, Doc, maybe you _do_ deserve this for what you did. All this-this miserable, endless nothing. Maybe this is the fate of all those Gasters, and _good riddance._ So, sure. A bunch of alternate Gasters, jerks who have hurt me even worse than you ever did. But guess what, Doc? You _haven't_ broken me. You never did. Cause you hesitated. You can pretend all you want that you're just this-this stupid, voidy mass of hate and anger and jealousy. But I know the truth. You _hesitated._ I won. And tonight? Heh. Won again."

Sans let go and withdrew. Gaster shrank back, the void seeming to compress around him, almost as if he wanted to make himself smaller.

The scene changed again, an image flickering into existence as if from a very old movie projector. Sans in a heap on the catwalk at the bottom of the Core, Gaster-Gaster as he was, still a monster, still alive-clutching at his own face, eyes wide with horror.

There was a sound like a tape being rewound and then Gaster spoke in his old, true voice.

 **"What have I done?"**

"A lot." Sans pulled himself back together with a long, exhausted sigh. Gelatinous ooze hardened into bone again, red faded into electric blue. The pain dimished into a distant ache. Sans hugged his knees.

"A lot of bad. Some good."

The image faded, leaving darkness again.

"SHE WILL. MAKE MISTAKES."

"Everyone makes mistakes. That's the point, Doc. People are too complicated to be just one thing. We're not one-dimensional." Sans cast a tired look out at the void and chuckled softly. "Though, heh. This place? It's gotta be at least five dimensions. Maybe six."

There was a long silence.

"AMUSEMENT."

"Mm?"

"A...MUSEMENT. THAT. WAS ANOTHER THING." Gaster paused and made a nondescript sound. "YOU. AMUSED ME."

"Heh." Sans smiled. "You'd groan at the puns, but sometimes I'd catch you smiling."

Gaster was silent for longer this time.

"MIS. TAKES. I WILL. CONTINUE TO. MAKE MISTAKES."

"Yeah. Like I said, everyone does. Best we can do is have someone there to remind us that we're more than just our mistakes. Paps is there for me. I'm there for Al. You used to let me be there for you."

"TOO. MUCH. TOO MUCH TO. ASK."

"Well. Still got a timeline to fix, don't we?" Sans shrugged. "I can't give up just yet. Plus, if you think I've forgiven you yet for all the shit you've pulled-here and before-then, man. You're more of an idiot than I thought. I'm not stupid. I know this isn't over. You're still gonna be a petulant asshole, aren't you?"

"AS I SAID. MISTAKES."

"Pfft. Mistakes. Yeah. Strapping me to a table and injecting me with Determination, that's. That's sure a _mistake_ alright."

Gaster didn't answer, but Sans thought he felt the void shrink back again.

"Still. Progress is progress. Well." He looked out at the void. "Not gonna ask you to promise not to pull this shit again. You broke every promise you ever made to me."

"I. AM. SORRY, SANS."

Sans froze.

"...Really?"

"YES."

"Heh. Haven't heard that from you in awhile."

"IT IS. TRUTH."

"So guilt now too, huh?" Sans sighed, unable to help but feel relieved. "Good."

Sans surged awake. He clapped both hands over his mouth. He didn't scream, but he did inhale sharply. His sheets were tangled in knots and soaked in sweat.

For a second he just hyperventilated and stared at the ceiling, watching the faint glow of magic color the ceiling. Electric blue tinged with yellow. Not red.

Sans slid out of bed and tumbled to the floor, curling up on his side and gritting his teeth. His hipbone ached where the imaginary needle had gone in. He felt along the ilium, but there were no marks, no holes.

It was just a dream, a dream like always, but Sans had to be sure. He pulled himself to his feet and padded down the hallway as quietly as he could to the bathroom. Once there, he flicked on the light and examined himself in the mirror.

He was a mess. His left eyesocket was still blazing. Sans squeezed it shut and let the magic die; when he opened it again, the usual white eyelight was back. He was trembling. He had actually gotten through to Gaster, had _finally_ had a modicum of success, but everything that had happened before that…

Sans checked his pelvis. No holes. Nothing at all. And yet it still ached.

He let his eye come alight again. Yellow and blue, no red. He summoned a single bone, though his magic struggled against his hold like always. It had gotten easier, but he was nowhere near perfect, not by a longshot. But the bone was white, wreathed in electric blue. Normal. No red.

The bone vanished and Sans let out a breath he didn't realize he'd been holding. He braced one hand against the mirror and rested his forehead on the edge of the sink.

"Just a dream," he whispered. "He hasn't gotten you yet. Heh. Hell. Looks...more like you got him."

It had been easy to stay calm in the dream, to just use his anger and pain and fear to force his way through, to finally make Gaster listen. It was just like that night in the Core, really. But here, awake in the middle of the night, hip aching from a wound that had never happened, it all felt...too real. Too much. The bathroom felt all at once tiny, like a mouth about to snap closed. Claustrophobic.

There wasn't a single room in this apartment that hadn't been touched by Gaster's influence. Even Papyrus's room. A few months back, Sans had awoken after a dream in which Gaster had showed Papyrus dying a thousand different ways. Sans had crept into Papyrus's room just to make sure he was still alive, and had ended up dozing fitfully while curled up in a corner. Papyrus had been very concerned the next morning.

"Can't stay here," Sans said, voice muffled by the edge of the sink. "Can't keep this up."

* * *

A week later, a day after King Asgore had announced that one Dr. Alphys was to be the next Royal Scientist, Sans went out to Snowdin to visit Papyrus at his station. It was the first time he had been out to actually see it. Papyrus had built the station himself out of cardboard, as the old one had been taken over by Doggo Jr.

"SANS! WHAT A PLEASANT SURPRISE!" Papyrus said when he spotted Sans. "IS WHAT I WOULD LIKE TO SAY! WHAT DO YOU THINK YOU'RE DOING SO FAR FROM YOUR STATION? GET BACK TO WORK, YOU LAZYBONES!"

"Don't get all hot under the collarbone, bro," Sans said with a wink. "I got the day off. I figured your shift was almost over, so I thought I'd come out and see the place. Nice digs. I like the sign."

"NYEH HEH! The Great Papyrus DID work very hard on it!" Papyrus beamed.

"I can tell. Nice view, too." Papyrus's station was settled near the forest, overlooking a small cliff. "All I can see from mine is the creek and water sausages."

"Water sausages are NEAT to look at, though! I like when they explode into puffballs!"

"You know, I've always wondered if you can eat those things," Sans said thoughtfully. "They're called 'sausages' after all."

"EVERYTHING IS EDIBLE IF YOU JUST PUT YOUR MIND TO IT!" Papyrus said, pumping his fist.

"You about done here, bro? I can walk you to the ferry. Got something to show you."

Papyrus gave him a very suspicious look. "You? SANS? WILLING TO WALK SOMEWHERE? I am MILDLY concerned."

"Nah, I think you'll like it." He _hoped_ Papyrus would like it.

"Then...very well. Let me gather my things!"

The walk back into the town was nice, leisurely even. Papyrus was always good to walk slowly so Sans's short legs could keep up with him. It was harder than usual in the snow. Sans had once sunk up to his neck in a snowdrift out here while he was practicing magic. He'd had to teleport himself out.

They chatted about their day. Sans told a few puns that made Papyrus groan and hide a smile behind a gloved hand. Papyrus told Sans about how he and Doggo had struck up a conversation about light blue magic.

"He is good at it, but I am even better!" Papyrus declared. "Well...that is possibly because his eyesight is so bad."

"Heh, still. I'm not surprised. You've been good at light blue magic for years now. Everyone been treating you okay out here?"

"Oh yes! The dogs are VERY friendly! I like them a lot! Although…" Papyrus sighed just a little. "None of them have exactly become my...friend? I have tried, and they are very nice! But they mostly just hang out together."

"Well, they are pack animals."

"STILL! THE GREAT PAPYRUS WILL NOT GIVE UP!" Papyrus howled as they entered town, making a nearby bunny monster give the skeletons an odd look. "I will make friends! I will make SO MANY FRIENDS!"

"A googol of friends."

"A-what?"

"It's a really, really big number."

"Oh! Then, YES! THAT MANY FRIENDS!"

Papyrus made to turn as they neared the short jetty where the ferry stopped, but Sans kept walking straight.

"Uh, Sans? We passed the ferry."

"Yeah, I know. Said I wanted to show you something, right? It's not far. Just up ahead."

"UGH, FINE! But if we miss the ferry, I blame YOU!"

"That's fair."

"Is it the Librarby?"

"Nope," Sans said as they passed it. "Man, they're never gonna fix that sign, are they?"

"Perhaps I will make that my next project as a sentry! Fix that TERRIBLE sign! And maybe see if I can't convince Grillby to move his entire restaurant to Hotland…"

"Aw, bro, no. Grillby's is the best part of this place."

"AS EVER, WE MUST AGREE TO DISAGREE."

They walked another block, passing a few houses. Papyrus made impatient noises.

"SAAAAANS! WHY DO I FEEL YOU ARE LEADING ME ON A WILD TEMMIE CHASE? Can't you just TELL ME what you want to show me? We're going to miss the ferry!"

"We're here," Sans said, coming to a stop in front of a house. It was a good size for how small Snowdin was, but was otherwise relatively nondescript.

"Here? What's here?" Papyrus peered at the house. "Do you mean the house? Does one of your friends live here?"

"I mean. One of my friends _might_ life here, so to speak." Sans walked up to the front door, pulling a set of keys out of his pocket. Papyrus hovered back on the street, clearly confused.

"Come on, bro," Sans called to him as he unlocked the front door. "Wanna check it out?"

"SANS, AS A MEMBER OF LAW ENFORCEMENT, SORT OF, I MUST INFORM YOU THAT YOU ARE TRESPASSING!"

Sans grinned at him and twirled the keyring around his finger. "It's not trespassing if you own it."

Papyrus frowned. "I...do not understand."

"Just come inside, bro. Check it out."

Sans went on in, certain that Papyrus's curiosity would get the better of him. The inside was relatively normal as houses went. One and a half floors, two bedrooms upstairs, a kitchen and a large living room downstairs. The carpet was rather violently colored, and the walls were a somewhat alarming shade of maroon, clashing horribly with the carpet. Sans kind of loved it. The place was mostly unfurnished, except for the occasional endtable.

Sure enough, Papyrus followed Sans a few moments later, looking uncertain and out of place.

"It's...empty? This is VERY strange! Oh, but I like the carpet!"

"Well, I would hope it was empty."

"Sans...I don't understand. Whose house is this?"

Moment of truth. Sans reached up and took Papyrus's hand. He opened his fingers and set the ring of keys in Papyrus's palm.

"It's yours, Papyrus."

His brother stared at the keys.

"I mean. Technically I had to put my name on the lease. But it's yours. Everything's taken care of. Down payment's squared away, rent will be fine so long as my job doesn't change. They said in a couple years you can probably pay it off and buy it, if you want. If you, you know. Like living here."

"I…" Papyrus trailed off. Sans couldn't remember the last time he had seen his brother speechless. Papyrus's fingers curled around the keys and he stared at Sans.

"It's...mine?"

"Y-Yeah." Sans rubbed the back of his head. "If you want it, I mean. I just figured...you said Snowdin was an okay place, and I know you...don't like our apartment much more than I do. And, you'll be closer to work here, so. I mean, I know you like getting up early, cause you're weird, but. You know. This way it's at least easier. You can get stuff done in the morning without having to rush off. And, um. There's a big kitchen. I mean, it's pretty big."

Sans was rambling and Papyrus was still staring at him.

"And, the second floor is nice. I know it looks kind of weird from here since it's set back so far, but it's, you know, it's spacious. The rooms are pretty big. Bigger than your room at the apartment. So, um. You can finally get that racecar bed you wanted."

Sans laced his fingers together behind his back, wringing his hands slightly.

"C-C'mon, bro, say something. Don't leave me hanging."

Papyrus finally looked away from him, turning to fully take in the house.

"How did-how did you manage to afford this?"

"I-It wasn't that hard actually." Sans scuffed at the carpet, toeing at a set-in stain. This could be going better. "Sold some stuff, saved up for the past year. Rent's crazy cheap out here. It's mostly just furry folk who have been here for years. Not many people move here, so. So it wasn't too bad."

"Sans…"

"And listen, if you don't like it, you can just say so. I-I can talk to the realtor. There's other places I can find. Or if you don't actually want to move out of the apartment, that's fine too. I. Heh. I really screwed this up, huh? Man. Heh. It was stupid to try and surprise you. I just figured, i-it's been a pretty crazy year, and I know I've put you through a lot lately, and, I dunno, I just wanted to do something nice I guess, but-"

"SANS!" Papyrus stepped up to him and clapped both hands on Sans's shoulders. "I LOVE IT! THIS IS-THIS IS AN INCREDIBLE GIFT, BROTHER! I LOVE IT! THE CARPET! THE SPACE! THE KITCHEN! LOOK HOW BIG THE KITCHEN IS!"

Papyrus let go and bounced away into the kitchen, cackling like a mad skeleton.

"IT'S HUGE! IT HAS A FULL SIZED REFRIGERATOR! I CAN COOK ANYTHING I WANT!"

Papyrus came tearing back out of the kitchen and ran to stand in the middle of the living room, arms spread wide. Sans stood there watching him, slightly dazed and incredibly relieved.

"AND LOOK AT THIS AREA! WE CAN PUT THE TV RIGHT HERE! AND THE COUCH OVER THERE! OH, AND MY FAVORITE LAMP CAN GO IN THAT CORNER! AND CAN I REALLY GET A RACECAR BED? REALLY?"

"Yeah, bro." Sans beamed at him. "Heh. You can get as many racecar beds as you want."

"NYEH HEH! SANS, THIS IS AMAZING! A HOUSE! A WHOLE HOUSE! I LOVE IT! THIS IS SO MUCH BETTER THAN THE APARTMENT! THIS IS A HOUSE WORTHY OF THE GREAT PAPYRUS!"

"Heh, I'm really glad you think so. You had me worried for a second."

"I WAS MERELY OVERWHELMED! AND-AND I MAY HAVE CAUGHT SOMETHING IN MY EYESOCKET FOR A MOMENT AND NEEDED TO COMPOSE MYSELF!"

"Oh yeah?" Sans grinned. "What did you catch?"

"NOTHING! NEVER MIND!" Papyrus folded his arms under his chin, staring gleefully around the house. "Sans, I love it, I really do! You are truly a WONDERFUL brother!"

"Heh." Sans tried to hide in the collar of his hoodie.

"Oh, but! Where will you sleep?"

"There's a second bedroom down the hall up there," Sans said, pointing. "But, you know, that's only if you want me here. I've looked at some smaller places in Waterfall that could work. I just know I'm not staying in New Home."

"Wait...what?" Papyrus looked caught off guard. "Only if I WANT you here?"

"Well, yeah." Sans shrugged. "I mean, well...you know, we're both adults. You're probably gonna join the Royal Guard eventually."

"DEFINITELY!" Papyrus corrected.

"Definitely," Sans said with a grin. "Meanwhile, I'm-"

Sans honestly hadn't thought about it. He would keep being a sentry, but then eventually he would fix the machine, and eventually he would set the timelines straight again. But that was far away. He hadn't given much thought to his own future.

He shrugged again. "I'm just doing whatever, I guess. So, you know. We don't have to keep living together if you don't want to."

"Are you...saying you don't want to live with me anymore?" Papyrus asked in a small voice.

"N-Nah, that's not...I just mean…" Sans scratched at his skull, looking away. "I know I'm not easy to live with. I just figured...you know, it's your house. It's up to you."

Papyrus stared at Sans for what felt like several minutes, his expression unreadable.

"Do you WANT to keep living together, brother?"

"I mean...only if you wanted m-"

"Just give me a straight answer, Sans, please."

Sans was quiet, tapping his fingers together. It felt wrong to admit to wanting anything. Selfish. He didn't want Papyrus to feel obligated to keep putting up with him.

But...Papyrus was asking for honesty.

"I, uh. Yeah. I mean. I want to. If you were o-"

Sans didn't finish because at that moment Papyrus scooped him up into a tight hug.

"THEN OF COURSE I WANT TO KEEP LIVING WITH YOU, BROTHER!"

"Ah, heh, jeez." Sans laughed into Papyrus's scarf. "You're squishing me, bro."

"THE GREAT PAPYRUS IS SO LUCKY! AN AMAZING JOB, AN AMAZING HOUSE, AND AN AMAZING BROTHER!"

"Aw, bro. If anyone's lucky, it's me. Every day, I'm asking myself, _house_ did I end up with such a cool bro?"

"NYEH! EVEN YOUR PUNS WON'T RUIN THIS TOUCHING MOMENT, SANS!"

"Hey, bro?" Sans hugged him a little tighter. "Thanks. Seriously."

He'd been worried. So worried that this wouldn't work, that Papyrus would hate the place, would think it was too much. Or that he'd love it and still ask Sans to leave. Even the coolest of brothers had to push their siblings away eventually, right?

Papyrus gave Sans a squeeze.

 _"_ And thank you too, brother."


	8. Perseverance

.

 **ENTROPY**

* * *

Chapter 8: Perseverance  


 _I think purple is a better look on you.  
_

* * *

Another human had fallen into the Underground.

Sans got the news when he was out practicing magic in the woods one day. His cell phone almost never went off when he was out here. The sudden noise startled him into summoning four Gaster Blasters.

"Holy-"

He let them vanish before they could fire and dug his phone out of his pocket.

"SANS! PLEASE TELL ME YOU ARE AT YOUR STATION!"

"Uh, yeah." Sans teleported to his station in Waterfall. There was no one around, thankfully. "Which one?"

He had started picking up shifts at a second station at the edge of Hotland. No one ever asked how he managed to be in two places at once. Double the work meant double the pay _and_ double the breaks. He was already starting to wonder if maybe he could swing a third. There was a vacancy at one of the stations deeper in Hotland, closer to the Core.

"BOTH OF THEM! ALL OF THEM! BUT ESPECIALLY THE WATERFALL ONE! SANS, PLEASE TELL ME YOU DIDN'T ABANDON YOUR POST!"

"Course not," Sans lied. "What's the big deal?"

"THERE'S A HUMAN, SANS! A REAL HUMAN! THEY'RE SAYING IT'S SOMEWHERE IN WATERFALL RIGHT NOW!"

"...Oh."

A human. Another human. What was this, the fifth? Technically the sixth. Sans scanned the cave and the edge of the creek, as if the human might pop out of the water sausages at any second.

He had forgotten. It felt stupid, but he had actually _forgotten_ that humans falling into the Underground was even a thing. The last time a human had fallen, Gaster had still existed. Sans's ribs tightened as he remembered. Green. The poor kid with the frying pan, who had just wanted to live a quiet life among the monsters.

"Anyone narrowed it down to more than just Waterfall?" He got up from his chair and stepped away, idly searching the cave.

"THEY THINK IT MIGHT BE NEAR THE TEMMIE VILLAGE!" Papyrus sounded borderline ecstatic. "HAVE YOU SEEN ANYTHING? HAVE YOU CAPTURED THE HUMAN YET? HAVE YOU BEEN PATROLLING ENOUGH? THIS COULD BE YOUR BIG CHANCE, SANS!"

"Heh. Slow down, bro." He sat back down with a sigh, hoping it sounded contented instead of worried. "I'm not nearly as into capturing humans as you are. But, nah. I haven't seen anything. Maybe I'll wander out, see if I spot them."

"YOU LAZYBONES! TAKE THIS MORE SERIOUSLY!"

"I'm always serious. Serious Sans."

"I just CAN'T BELIEVE the human got past my flawless puzzles and traps! They were ONE HUNDRED PERCENT PAPYRUS GUARANTEED to capture a human!"

"They must've gone by last night or something."

Traversing Snowdin in one night without anyone noticing was no easy feat. It was a sleepy town, but it was also home to pretty much all the Guard Dogs in the Underground. Either this human was clever or…

"Is everyone okay, though? No one's been hurt, right?"

"EVERYONE IS PERFECTLY FINE! A human wouldn't REALLY hurt anyone intentionally, RIGHT?"

Sans stifled another sigh. "Sure, bro. You're probably right."

"I know they're our enemies, but GOOD ENEMIES HAVE HONOR! AND VALOR! AND INTEGRITY! AND OTHER GREAT VIRTUES BEFITTING THE PERFECT RIVAL! Actually, Sans…"

Papyrus lowered his voice conspiratorially. Sans tried not to be worried.

"What...does a human actually look like?"

Sans couldn't help a relieved chuckle. "Heh. They kinda look like skeletons. But with hair. And more muscles."

"WOWIE! MUSCLES! They must be quite STRONG! ALMOST AS STRONG AS THE GREAT PAPYRUS!"

"Almost." Sans leaned back in his chair. "Anyway, I'll keep an eyesocket out, bro. Take a look around. If I see any Temmies I'll ask what they've seen. Other than Temmie Flakes, at least."

"SANS, DID YOU HEAR? Undyne said that if anyone captures a human, they can be IMMEDIATELY CONSIDERED FOR A ROYAL GUARD POSITION!"

"Undyne?" Ah, right. That was the name of the Captain of the Guard. Sans had never met her. Presumably, she was busy running the Royal Guard and didn't have much time for random sentries. Sans remembered that she'd only been the Captain for a few years now, but that she was apparently incredible. Papyrus wouldn't stop gushing about her.

"Well, uh, think I'd have to deny the offer. Already so busy being a sentry, yanno. Plus, can you imagine me in the armor?"

Papyrus was quiet for a moment while Sans's grin spread.

"...Okay that is a GENUINELY AMUSING image."

"Imagine it. I'd be like one of those roly-poly bugs. Rolling from place to place."

Papyrus was tyring _very_ hard not to laugh on the other end.

"I'd be worse off than Greater Dog or his mom. On the plus side, I could get another job as a disco ball."

"SANS! STOP!"

"Heh, sorry, bro. Didn't mean to make you _bust a rib."_

"NYEH! JUST GO FIND THAT HUMAN, SANS!"

Papyrus hung up before he could actually break out laughing. Sans did it for him, chuckling as he pocketed the phone. A few nearby Echo Flowers took up the sound. He folded his arms behind his head and leaned back in his chair, grin fading slowly as he peered up into the darkness of the cave ceiling. A few glittering stones twinkled from dozens of feet up.

Another human in the Underground. He wondered if it was another kid this time. He wondered if it was always going to be kids. Why was it always kids? What humans up there were letting their children climb such a dangerous mountain? From how Sans understood it, humans considered Mt. Ebott to be cursed-haunted, even. So why in the world had it been nothing but kids thus far?

It would go like it had before. No matter how clever this human was, eventually someone would catch them and they would either die or be handed over to the King. Maybe they would kill a few monsters before that happened, maybe not. Either way, it wasn't Sans's responsibility. Not anymore. It never should have been in the first place. Besides, if the human was near the Temmie Village, they were way past his sentry station.

It was too bad that Papyrus had missed out on everything, though. One of Papyrus's many dreams had always been to capture a human, or at least meet one. Humans and the Surface fascinated him, as it did most monsters. It would be nice if Papyrus could at least see a human one of these days. So long as they were one of the nice ones. That was the real gamble. What would happen if Papyrus met a human that _wasn't_ nice? People didn't always...understand Papyrus. They underestimated him, misjudged him. People liked him well enough, but Sans knew that even the dogs thought Papyrus was a bit too kind and soft. Ironic, considering they were dogs.

There was also the fact that Papyrus didn't know what actually _happened_ to humans who fell into the Underground. He knew they were captured and sent to Asgore, and he knew that the King was collecting souls, but he didn't know what that...entailed. Sans had never told him. He doubted the dogs had had the heart to tell him, either.

And of course there was the chance that whatever human Papyrus met ended up being the dangerous kind, like Gaster had always warned about. It had never occurred to Sans before now, but with Papyrus a sentry and aiming for the Royal Guard, him meeting a human was going to be almost inevitable. With Sans stuck at stations Waterfall and Hotland, he might not even be there to help his brother. Not that he would really be much help. Papyrus was an amazing fighter, but...

Sans got to his feet. All this thinking was making his skull itch.

He teleported deeper into Waterfall, landing in a secluded corner near one of the ferry stops. It was a well-trafficked area, but Sans had gotten very good at finding "shortcuts" to out of the way spots. No one saw him. Practicing magic had worn him out, and he could use some Sea Tea if he was gonna make it through the rest of his shift-technically shifts, plural. Sea Tea worked almost as well as coffe, plus it was cheaper. There was a shop near here run by an ancient tortoise monster named Gerson, and he sold the best Sea Tea in the whole Underground.

He was also a bit of a gossip.

Sans stuffed his hands in his pockets and headed for Gerson's side cave. Shyren was on her way out, the creature that made up her lower body carrying a bag overflowing with Sea Tea and Crab Apples. Sans smiled at them both.

"Hey there. Heh, looks like you cleaned old Gerson out. Hope there's still some Sea Tea left."

Shyren smiled faintly, hiding behind her hair-like fins. She looked sad and worn out; moreso than usual.

"Hello," she whispered, a single note-shaped bullet floating out of her mouth and drifting to the ground. Her voice could be dangerous, so she almost never spoke above a whisper. She apparently had a lovely singing voice when she got up the courage to try, though.

"How's your sister doing?"

Shyren's face fell even further. "Not...much change. But. Thank you for asking." She gripped the bag tighter with her lower body. "The...Sea Tea is helping."

The Shy sisters had always been inseparable, almost as much as Sans and Papyrus, but Shyren's sister had been unwell for awhile now. In the past month or so she had even stopped leaving their pond altogether. Monsters didn't get sick in quite the same way as humans did, but there were still plenty of things that could affect them. Bad magic, bad monster food and so on. Sometimes monsters just got sick for no apparent reason.

Sans knew the feeling.

"Well, that's good at least. I hope she gets better soon. Good luck, okay?"

"Mm...thank you, Sans."

"And, uh, hey. Be careful out there. I heard there's another human around."

Shyren's eyes widened slightly. "Oh...goodness. Th...Thank you for the warning." A few more music notes tumbled out of her mouth. "That's...the fifth, isn't it? That means...we're almost...there."

"Heh. Yeah. Guess so. I'll see you around. Tell your sis I said hi."

Shyren bobbed in agreement and left. Sans went on in to Gerson's, stifling a sigh. Poor girl. Sans didn't know what he would do with himself if Papyrus ever got sick. Papyrus had injured himself plenty in the past, but Sans didn't think he had _ever_ gotten sick. That was always Sans's job.

How had Papyrus dealt with that? Sans had never asked.

He was still thinking too much.

Gerson was stocking shelves when Sans went in. The old tortoise grinned when he spotted Sans.

"Waha! If it isn't Sentry Sans. Had a feeling I'd be seeing you today."

Sans grinned right back at him. "Hey, old timer. Just picking up some Sea Tea. And you can _still_ stop calling me 'sentry,' you know."

"Not a chance. Rolls off the tongue too well. 'Sides, I thought you preferred it to Sans the Sneak!"

That at least was true. Sans set a few G on the counter and Gerson passed him a small bottle. The contents glowed faintly.

"I'd almost think you were picking on me. Except I know you give _everyone_ a hard time."

Gerson winked, or at least seemed to. It was hard to tell, considering his right eye was closed almost all the time. Some kind of old battle injury, he always said.

"Keeps monsters on their toes, haha! Plus it's the job of the old to pick on the young. And all of you are young to me."

Gerson cackled and Sans chuckled as well. He had always liked the old tortoise. The guy had a great sense of humor, and he was full of stories-when he could remember them, at least.

"Any interesting news?"

"One of the Temmies found a hardboiled egg in the dump and is trying to hatch it. Those guys are a riot, eh? Apparently a mushroom monster appeared in their village a week ago, and the poor guy can't even leave! Rooted to the spot and all. Imagine! I hear he's philosophical about it, though. Sounds like Onionsan is the last guy living in that big lake over yonder. Alliumsan and Vidaliasan both moved out to New Home. What's an octopus gonna do in New Home, I ask you? At least they're smaller. Maybe they can find a decent pond, eh? Poor Onionsan. Talk about a big monster in a big pond, huh? Wa ha ha!"

Sans propped his elbows on the counter and set his chin in his hands, grinning while Gerson rambled on.

"That's too bad. Always was a fan of the _sans-es."_

"Ha, that's a good one! But don't interrupt! Let's see...two Aarons had an arm-wrestling fight that lasted four hours! They both ended up passing out right on top of each other. I've never seen so many Woshuas cleaning up one spot in my whole life! Ah, and I heard that they've run short of bridge seeds in some of the upper caverns. Must be making the commute into New Home rough. Some little guy has taken it upon himself to ferry people across the dark lake up there. And, well...that's about it, I think. You know Waterfall! Always pretty quiet around here, you know?"

Sans shrugged. "Yeah, true. Snowdin's not much more lively. Except when there's a party at Grillby's, anyway." He took a sip of his Sea Tea and felt himself wake up a little. It was refreshing, with a sort of seaweed aftertaste that wasn't terrible. "By the way. Did you hear there's another human in the Underground? Apparently they're somewhere in Waterfall."

"Oh, I heard," Gerson said, and his grin turned mischievous. "Fact, they were just here!"

Sans paused with the Sea Tea halfway to his mouth. "...Oh?"

"Yep! Just a few hours ago. Quiet little thing. Bought some tea and Crab Apples, chatted a bit and then went on their way."

Sans eyed him. "And I'm guessing you didn't tell any sentries or guards?"

"Nah. Didn't see too much point to it! They were harmless. More curious than anything. Full of questions! They wanted to know what Sea Tea did, and who Asgore was, and about the Delta Rune." He jerked a thumb over his shoulder to the symbol emblazoned on his back wall. "Kid was taking down notes the whole time. They said they wanted to write a book when they got to the Surface. Tell the whole world how interesting the Underground was. Isn't that just charming?"

Sans sighed quietly to himself and slid his elbows off the counter.

"Now, now. Don't pretend to be upset." Gerson smiled faintly. "I know you're too lazy to be mad about not catching a human. I know you too well, Sans! Plus I know you don't like this any more than I do."

Sans met Gerson's gaze for just a moment before looking away.

"Heh."

"Maybe this one will make their way out," Gerson said, almost wistfully. "Write that book. Wouldn't that be something?"

Gerson knew full well that no human could cross the barrier without a monster soul in tow. Sans wondered if the human knew that as well.

"You know…" Sans polished off his Sea Tea and set the bottle back on the counter. "This old friend of mine used to tell me that humans were always dangerous. Always bad news. He was old enough to remember the war and the Surface. Kinda like you."

"When I can remember any of that ancient history, at least! Wa ha ha!"

"Heh. Kinda funny you both came away with such different opinions about this stuff."

Gerson chuckled and set the empty bottle in a recycling bin, grunting as his joints creaked.

"I used to be different. Was a real hothead back then! The Hammer of Justice, they called me!"

"Right. I remember from the last couple thousand times you've told me."

"Ha! As cheeky as ever, aren't you? Still. What do you think someone called 'The Hammer of Justice' really got up to?" Gerson's expression went grim for just a split second. So fast that Sans almost missed it. "War and such does odd things to people. You either learn to set it aside, or you don't."

Sans was quiet for awhile.

"...Too bad I won't be in that book of theirs. I coulda thought of some great jokes. Show the humans how real humor is done."

Gerson howled with laughter and slapped the counter. "I don't doubt it for a second!"

They traded goodbyes and Sans left, teleporting again once he was out of sight. This time he landed at his station at the border of Waterfall and Hotland. The abrupt change from the cool, damp air of Waterfall to the dry heat of Hotland was a little dizzying. Sans took a seat at his station and propped his feet up on the counter.

A book, huh?

He thought of the boy with the frying pan. He had wanted to stay in the Underground, live among the monsters, keep on cooking food for people. What was it he'd said?

 _Everyone knows the war was a huge mistake._

It didn't matter. This was the way things were. Maybe when Sans finally got the machine working and the timeline had been fixed, maybe...something could be done about these kids. The Determination of four souls was enough to generate a Reset that a monster could utilize. There had to be other things it could do. Not a Reset, but maybe…

He wasn't sure. This didn't matter, either. There was no point in thinking about it until the machine was fixed, and there had been absolutely no improvement on that front. Everything Sans had tried thus far hadn't worked. Alphys was still helping when she could, but she was so busy as the Royal Scientist that Sans barely even saw her anymore. They hadn't even spoken in almost a month.

At least he was starting to get his magic under control. At least he and Papyrus were happy in Snowdin. At least Papyrus was getting along with the other sentries and guards. At least things finally seemed a bit stable.

At least he didn't have to kill a human this time.

* * *

One of the major perks of their house in Snowdin was that it had a basement, accessible only by a door in the back of the house. Papyrus knew it was there, and the one time he had asked Sans what was down there, Sans had answered that it was just "nerd stuff." That had been enough to keep Papyrus from snooping, though Sans kept the door locked all the same.

Sans had turned the basement into a very small laboratory. Technically it was more of a workshop, big enough to house the time machine, some tools and a good-sized table for drawing up blueprints and such. Sans had taken to keeping everything Gaster-related in the lab, where no one could stumble on it accidentally. He had managed to do a final sweep of the old laboratory in Hotland before the place had been renovated, but he had found nothing. If there was anything left behind there, it would either be destroyed in the renovations or eventually dug up by Alphys.

He had been by her laboratory twice since the renovations had been completed. It looked as good as new, and Alphys had even turned the second floor into her living quarters. She had taken awhile to settle in; Sans knew that she missed New Home.

Today they were both in Sans's lab while Papyrus was on sentry duty, as it was the first time in months that their days off had coincided. Alphys seemed more stressed than usual, which was saying something. She was fidgeting and writing down equations for her own work while Sans tried to do some rewiring on the machine.

"Pass me the screwdriver?" he said, sliding an arm free and holding out his hand. He was dangling halfway into the bottom of the machine, surrounded by wires and tubes.

"What? Oh. Which one?"

"The Phillips. The second one." He pointed, though he had no idea which direction he was pointing. After a moment he felt her press the screwdriver into his hand. Sans leaned further into the machine.

"So what am I looking for?" he called as he unscrewed a small panel.

There was no answer.

"Al?"

"Yes, sorry, uh. There should be quad core CPU behind the panel. Uh, it'll look like a pretty big microchip."

"Sounds like an oxymoron." Sans pulled out the last screw and removed the panel. Sure enough, there was something that looked like a microchip behind it. Though he wasn't entirely sure. All this mechanical, engineering stuff was more Alphys's field, but with her headspines she couldn't fit in such a tight space. She was supposed to be walking him through the process.

"I'm guessin't it's not supposed to be blackened and melted on one end?"

No answer.

"Al."

"Hold on, this-this calculation is giving me trouble…"

"Sure. I'll just dangle here." He sighed quietly. "What're you working on?"

"It's a secret. And if it's melted, just pull the whole thing out. I c-can build another CPU, that's not a problem. Jeez, that'll be what, the fourth one I've needed to build for this thing?"

Sans removed the destroyed chip and extricated himself from the guts of the machine. A cable had hooked around one of his vertebrae, so it took a little while.

"Uh, you know...we don't have to work on this today." He sat on the floor of the machine, wiping sweat from his skull and studying Alphys's face. She was seated at the table a few feet away. Her snout was buried in a notebook and her face was screwed up in concentration. She didn't even glance up.

"We could do more hull patches, that's easier. Or-"

"No, it's fine, just. Sorry." She glanced up quickly. "I-I've just got so much on my plate, you know? It's my day off b-but it's not even really my day off cause I've gotta...I need to get this stuff done."

"That's what I mean. We don't even have to work today if you want, I just figured-"

"I-I said it's fine! Just...just give me a _second_ and let me finish this."

Sans shut up, looking down at the burnt chip in his hands. The damage to the machine was very thorough. This had to be the fifth microchip-type thing they'd found that was burnt to a crisp. Alphys had been slowly replacing them, since they were some of the few things that could actually be replaced. Still...building magic microchips, or whatever they were, had to be difficult and time consuming. She was already insanely busy.

He stayed quiet until she finally set her pen between the pages and closed the notebook. She sighed and leaned back in the chair, rubbing the back of her neck.

"Ugh, that'll have to be good enough I guess."

"You want me to look it over?"

"You can't. It's confidential. Asgore keeps reminding me not to share my work. I think he's worried...it's almost like he subconsciously knows that Dr. G pulled some k-kind of crap and wants things to go right this time."

"Gaster."

"Yeah, right, Gaster. Ugh. Anyway, wh-what were you saying?"

Sans held up the burnt CPU. Alphys made a face.

"Jeez. You know, I-I think I've said it before, but it's k-kind of a miracle that you're alive."

"Heh, I get that a lot."

"Oh-no, I didn't mean-"

"No, it's okay, I'm just messing with you." Sans rubbed the back of his skull, feeling awkward. Things had never felt awkward with Alphys until now. "Uh, so...you know, no rush on building a new one. Like you said, you got a lot on your plate."

"Yeah…" She scrubbed at her face with one hand. "I'm sorry I've been so weird and...snappy today."

"It's okay."

"No it's not. Y-You're my friend, I-I shouldn't take out my stress on you. It's just...I've been the Royal Scientist for a year now and I-I've got nothing to show for it. N-Nothing but some more Mettaton improvements, and some random robots...Asgore wants results and Mettaton wants results and the whole _Underground_ wants results...a-and I just haven't been able to deliver. D-Did I tell you Asgore is letting me start to work with human souls?"

Sans grinned hugely. "That's great news, though. With soul power we can finally-"

Alphys held up a hand. "B-But hold on, Sans. I've only got access to one soul right now, and they put a sort of tracking spell on it to make sure it doesn't leave the lab. Everything's being supervised right now. I-I can't just suddenly start working on random parts for a machine n-no one knows about. I told Asgore I was looking for a way to bring down the barrier, but...I-I mean Resetting to the past and making the barrier not exist in the first place doesn't really count. It's just...it's c-complicated."

Sans draped his arms over his knees, letting his hands dangle.

"Yeah, I get that. Trust me. I'm not getting my hopes up. I'm...heh. Kinda too much of a realist to ever get my hopes up. Still, him letting you study a soul is a step in the right direction."

"True. It's just hard to focus on all this Royal Scientist stuff _and_ th-the machine on top of that."

Sans stared at the chip in his hands.

"I mean, Al, you don't have to keep working on this with me. It's my responsibility, after all."

"Ugh, that's not what I'm saying! Obviously I want to keep working on it, I want to save my dad. I-It just can't be a priority, you know?"

"Okay, okay. I understand, really."

He reminded himself that she wasn't really mad at him, at least not entirely. She was just stressed and frustrated. He knew that feeling. It was just hard not to feel like a burden. The machine, Gaster, the timeline itself, all of it was Sans's responsibility, not Alphys's. He was the one who remembered. He was the one who had failed to stop it in the first place.

There was a silence.

"Maybe...when things settle d-down a bit and I've impressed people with another good experiment and I've got access to all five souls, then I can refocus on all this."

"Five?"

"Yeah. Didn't you hear? They, uh, found that human that was roaming around."

"Oh."

So much for that book of theirs.

"I heard they got all the way to the castle, and then Asgore...well." Alphys shrugged. "I think the Royal Guard is really embarrassed they let a human get that far. I-I know Undyne is really mad."

"You know Undyne?"

"I-I mean, sort of? Kind of. Not really. I-I've seen her from a distance a few times?"

Alphys went a bit pinkish. Sans grinned.

"Anyway! I overheard her saying it was dishonorable that the guards couldn't even catch one puny human. And that the sentries weren't doing their jobs right."

"Uh oh."

"So, um...I'd watch your back...ha ha…"

"Thanks for the warning. So...what color did the soul end up being?"

"Purple, apparently."

Sans nodded.

"Welp. Should we get back to work?"

"Y-Yeah. You might as well get some of that wiring done, right? Um...I won't get distracted this time. I'll talk you through it. So, um, okay, back in that chamber where the CPU was, you should find a cluster of red wires…"

* * *

Two days later Sans overdid it a little during magic practice and fell asleep within minutes of arriving at his Hotland station. He was woken an hour or so later by someone banging on the station counter.

"Hey, you! Wake the hell up!"

Sans jolted awake, left eyesocket flickering blue for just a split second. He had never been a fan of sudden noises or sudden movements, and especially not combinations of the two. He blinked and stared up at two tall monsters standing over his station. Both of them were in the full plate armor of Royal Guards. The one who had been pounding on his sentry station had her helmet off and tucked under one arm. She was a blue fish monster with a missing eye and red hair.

"Huhwhat?"

"You were sleeping on the job! What kind of sentry falls asleep at his station?!"

All of them except for Papyrus, Sans was pretty sure, but he knew better than to say so.

"Sorry. I was just resting my eyesockets. Don't worry, I'm working myself to the _bone_ here."

The fish monster's lip curled over jagged teeth. Sans wasn't sure if it was a smile or a grimace or both.

A blue fish monster...why was that familiar?

"The whole point of a sentry is to be alert and vigilant! What the heck do you think we're paying you for? I can't have my sentries sleeping on the job!"

Ah, right. Blue fish monster in the Royal Guard. This had to be Undyne.

His boss.

Oops.

"Uh, well. Won't let it happen again?"

"You'd BETTER not!" She braced both hands on the counter and leaned down, glaring at him through her one yellow eye. "What if a human had come through, huh? Or were you sleeping the other day too?! Is that why the human got through here with no one noticing?"

She had to be one of the most intimidating monsters he had ever met.

"Uh, actually I was at my other station around then."

"Your-what?"

"Ohhhh, I've heard of this dude," the other guard piped up. "Yeah, he's one of those, like, skeleton guys?"

"I mean, I noticed that part," Undyne said, folding her arms, still glaring at Sans.

"Yeah but, like, one of them's in Snowdin, and the other one, like, somehow has two sentry stations?"

"That's me." Sans put on a winning smile. "I'm Sans. You must be Undyne."

"How does one monster have two sentry stations?"

"I have a great work ethic," Sans said, winking. Undyne narrowed her eyes.

"Alright, whatever! I'll be keeping my eye on you, skeleton. All the sentries and the whole guard have been slacking off WAY too much lately! I'm starting to think all of you need some extra training! _Mandatory_ training! Running laps through the garbage dump, hitting targets, leaping over fiery chasms!"

Great. More work. "I've never been too great at jumping. Stubby legs and all."

"This is what I'm talking about!" She summoned an electric blue spear out of thin air and slammed it into the ground with a thud. Sans flinched. That was an awful lot of destructive magic all at once, and too close for comfort. Undyne had to be incredibly strong. Between that and this bombastic personality of hers, it was no wonder she'd become the Captain of the Guard.

She and his brother would get along.

"Don't let me catch you sleeping again, punk!"

With that, she spun on her heel and marched away, leaving the spear planted in the dirt behind her. The other guard gave Sans a small, parting wave and followed.

Sans watched the glowing spear slowly dissipate into the air.

"Well, that happened."

He'd have to tell Papyrus that he had met Undyne. He'd totally freak.

"I can't BELIEVE she offered you special training and you DIDN'T EVEN TAKE IT! Wait. WHAT AM I SAYING? OF COURSE I BELIEVE IT!"

"You know me too well, bro."

"But she's right, though! EVERYONE BUT THE GREAT PAPYRUS HAS BEEN SERIOUSLY SLACKING OFF! I CAN'T BELIEVE A HUMAN GOT ALL THE WAY THROUGH THE UNDERGROUND...AND NO ONE EVEN NOTICED! NYEH!"

Sans gave a languid shrug. "They must've been a pretty clever human."

"But...UNDYNE! What is she like? Is she as cool as me?"

"No one's as cool as you, Paps. She's, uh. Very lively. You'd like her."

A strange look came over Papyrus's face. "Hmmmm…"

"Mm? Bro? I know that look. That's the 'I'm gonna go get into trouble' look."

"HMMMMMM!"

"Papyrus," Sans said, grinning and dragging out his name as much as he could.

"I'M SURE I DON'T KNOW WHAT YOU'RE TALKING ABOUT, SANS! THE GREAT PAPYRUS NEVER GETS INTO TROUBLE!"

That night was a Gaster dream. Sans sat at the bottom of a pitch black ocean, knees to his chest, strange shapes moving through the dark.

"What does a bone monster use to get into his house?"

No answer.

"A skeleton key."

The water murmured.

"What's a skeleton's favorite instrument?" He paused, even though he knew there would be no answer. "A trom _bone._ Though a xylo _bone_ works, too. Or a _clavicle_ chord, if you're really daring."

There was a puff of sound, almost like laughter.

"How do you make a skeleton laugh?"

"YOU TICKLE HIS FUNNY BONE." Gaster's voice floated behind him. "YOU HAVE TOLD THAT ONE. THREE MONTHS AGO."

"Did I? Sorry. Not always easy to come up with new material. And you're a pretty tough crowd."

Something dark swam close, then veered off into the nothing. Sans watched as twisted rock formations rippled in the distance.

"Did I ever truly amuse you? I don't remember if I ever actually made you laugh. Maybe you were just _humoring_ me. Heh."

"YOU AMUSED ME," Gaster confirmed, his voice far off. "BUT NOTHING IS PARTICULARLY AMUSING. ANYMORE."

"We could work on something else instead...if you want. Some other piece."

The ocean filled with static. The imagery behind it shifted. Sans saw glowing shapes appear, and when the static faded, the shapes resolved themselves into hearts. Light blue, orange, blue, green, purple.

"Right."

"PURPLE. THE COLOR OF PERSEVERANCE."

"I wondered."

"A COLOR THAT WOULD SUIT YOU."

"I'm more of a blue guy," Sans said, plucking the sleeve of his hoodie.

"BLUE." Gaster sounded thoughtful. "YES."

"What's that supposed to mean?"

"SOMETHING IS COMING."

"So you keep saying."

"YOUR PERSEVERANCE WILL FAIL YOU."

"Cool."

"BE CAREFUL OF-"

There was a piercing sound and the ocean shattered. Sans jolted awake and almost fell out of his bed. The sound happened again and Sans slapped at his nightstand until he grabbed his phone. He fumbled with the buttons, still ninety percent asleep. What time was it?

"What? Hello?"

"Is this Sans?!"

That voice was pretty unmistakable, even though Sans had only heard it once.

"Undyne? Uh...sup? What time is it How did you even get my number?"

"It's morning! Were you still asleep? Jeez! Wake up already! Your brother is at my house and you need to deal with him!"

"...What."

"He showed up last night, at like, midnight and LITERALLY started begging me to let him join the Royal Guard! I thought, aw jeez, not another one of these guys! So I slammed the door in his face! But he was still there when I woke up this morning, just sitting there by my front door!"

"Is he...okay?" Papyrus had been missing the entire night and Sans hadn't even noticed. When in the world had Papyrus gotten so sneaky? Sans was usually good at waking up at the slightest sound.

"OF COURSE HE'S OKAY! Maybe a little tired? I have to admit, I didn't expect YOUR brother to be so...well, dedicated!"

"Well, that's Papyrus for you. He's kind of amazing. So you need me to come out there and collect him?"

"Yeah, he's kinda passed out on my couch right now? I don't think he's used to the damp in Waterfall. It's funny, he told me he never sleeps! What a spirited guy!"

"Heh." Sans couldn't help chuckling. He knew they would get along. This was probably going to be bad for his health.

"Alright, I'll head out there. Or...where do you live, actually?"

"A few caves west of the ferry stop. You know the Blook farm? They're my neighbors."

"Okay. I know the area. Be there soon."

Sans hung up and heaved a sigh. He checked the clock on his nightstand. Nine in the morning. An absolutely ungodly hour.

He got dressed and teleported to the ferry stop, then walked the rest of the way. Shortcuts were best used somewhat sparingly, if only to keep people guessing.

Undyne's house was unmistakable, built to resemble the head of a giant, angry fish. Sans could think of nothing more appropriate. There was piano music issuing from the house as he approached. The music stopped when he knocked, and a moment later Undyne answered, dressed in civies.

"Hey, that was quicker than I thought it would be! Maybe you're not as lazy as I thought!"

Sans grinned. "Nah, I'm exactly as lazy as you thought. Where's Paps?"

"SANS!"

Papyrus appeared from out of nowhere and practically tackled Sans. The next thing he knew, he had been scooped up into a hug.

"Holy crap."

"SANS! CAPTAIN UNDYNE AGREED TO GIVE ME SPECIAL TRAINING!"

"Uhh…" Sans said as his brother spun in place. "Congrats?"

"I told you, it's just Undyne!" Undyne waved a webbed hand. "You can drop the Captain part. No formalities in my Guard! Anyway, I told him I couldn't let him into the Royal Guard just like that, but special training? That I'm totally down for! I like seeing sentries with initiative!"

"No one's got more initiative than my bro."

"NYEH HEH HEH! I SHALL BE A ROYAL GUARD IN NO TIME AT THIS RATE, BROTHER!" Papyrus set Sans down and Sans wobbled a little, dizzy from the spinning. "UNDYNE, THANK YOU FOR THE MILLIONTH TIME! And...SORRY FOR WAKING YOU UP LAST NIGHT, THOUGH I DON'T UNDERSTAND HOW SOMEONE LIKE YOU COULD BE NAPPING IN THE MIDDLE OF THE NIGHT!"

"Think that's just called sleeping, bro."

"Ha!" Undyne grinned, showing every single one of her sharp teeth. "I like your spirit, skeleton! Training starts this time tomorrow, and you'd better be on time! Or I'll make you run laps!"

"I LOVE RUNNING LAPS!"

"ME TOO!" Undyne yelled and gave Papyrus a playful punch in the arm.

Sans resisted the urge to bury his face in his hands. These two were going to kill him.

"Anyway, in the meantime, I think Paps could use another nap before his shift."

"NONSENSE! I TOOK A TEN MINUTE NAP ON UNDYNE'S COUCH AND NOW I'M BRIGHT-EYESOCKETED AND BUSHY-TAILBONED! Or something like that! BUT! I should go prepare for my shift!"

He turned to Undyne, clasping both hands together and beaming.

"But THANK YOU AGAIN, UNDYNE! FOR THE BILLIONTH TIME! I WON'T DISAPPOINT YOU!"

"You'd better not or I'll give you the noogie of your life!"

"Go on ahead, bro," Sans said, patting Papyrus's arm. "I'll meet you at the ferry. I wanna talk with Undyne for a sec."

"Yes! You two should become friends as well! I will see you soon, brother! When you have both become BESTIES!"

With that, he was out the door, cackling. Undyne laughed and waved goodbye. Sans stuffed his hands in his pockets and sighed.

"Man. I haven't seen him that happy in a few weeks."

"He's really cool! And a huge dork! Not at all what I expected after meeting you."

"Well, I've got the dork part down at least. Anyway...I wanted to ask you a favor."

Undyne smirked. "Aww, are you gonna tell me to go easy on your big bro? Cause THAT'S NOT HAPPENING!"

"...Actually, I'm the big bro. Technically speaking."

Undyne stared at Sans for a moment, then burst out laughing. Sans chuckled. Her laugh was kind of infectious.

"That's hilarious! But you're so short!"

"Right? It's pretty great." He kind of appreciated the bluntness. Most people went either the mocking route or the apologetic route, and both were always mildly annoying. And besides, it _was_ pretty hilarious-a little big brother. A joke unto itself.

"Anyway, nah. Papyrus can handle whatever you throw at him. Just wanted to ask you to be nice to him."

Undyne blinked her one eye. "Nice to him?"

"Yeah. Paps is a really good guy. He deserves people to be good to him, yanno?"

"Or what? You'll beat me up?"

"Heh." He winked at her. "But you like him, I can tell. So I don't think I have to worry."

She snorted and folded her arms. "You're a weird one, Sans. Of course I'll be nice to him! As nice as a captain can be, anyway! Ha! Anyway, get out of my house! I have important work to do!"

Sans left, shaking his head and chuckling to himself. Those two were going to get along like a house on fire. It should be fun to watch-so long as Sans kept a safe distance from the inferno.


	9. Eat Your Greens

.

 **ENTROPY**

* * *

Chapter 9: Eat Your Greens  


 _Unless you learn to face danger head-on...you won't last a second against me!_

* * *

Sans woke up one afternoon and couldn't remember Gaster's name.

It took three hours of diving into the notes he kept in his lab, of reading the name "Gaster" over and over to make it stick in his skull again. W.D. Gaster. The Royal Scientist before Alphys. He had fallen into the Core and been shattered. Doctor Gaster.

Sans sat for awhile on the floor of his lab, surrounded by scattered notes and blueprints, the heels of his hands pressed to his eyesockets. It was slipping away. It had been ever since he stepped out of the time machine. He folded his hands in front of his mouth and peered across the room to where it stood, currently sitting in a corner of his lab and covered with a tarp. The more time passed, the more it all faded. It was a constant fight not to forget.

If he forgot Gaster, he would forget the rest of it. The good parts, the bad parts, the true consequences of a Reset. He would forget that the timeline was a fractured mess that still needed repairing. He would forget the figure that still haunted his dreams, lurking in the dark, still waiting for a lapse in diligence.

How long had it been now? Three years? Four?

W.D. Gaster. The Royal Scientist. Shattered. Gaster, Sans, an entire science division. Physicists, chemists, magic technicians, engineers. And three of them working on Reset. Sans, Gaster and…

Doctor...he had been a lizard monster. Green scales. Alphys's father. It began with a B. Sans scrubbed at his face.

"Just think. Come on, think. Don't forget."

He cast around for the old photograph of them, but it was somewhere in the mess of papers around him. Desperate, he grabbed a blank piece of paper and a pen instead.

"Me, Gaster and…"

Sans was no artist by any stretch of the imagination, but right now it didn't matter. He sketched three figures on the paper-one tall, one average, one small. Funny how that had worked out. He finished drawing a few headspines on the medium monster and paused.

"B...Betas. Dr. Betas."

He sighed in relief, shoulders sagging. It felt like a feat, almost, as if he had just run a marathon. It was _exhausting._

Gaster, Sans and Betas. Sans peered at his handiwork, unimpressed. It was hard to tell who the three figures even were. As an afterthought he wrote _don't forget_ in the corner.

The lab was a mess. He couldn't exactly rely on Papyrus to clean this one up. Sans hauled himself to his feet, bones creaking slightly. He started gathering up all the papers and blueprints, finally digging out the photographs from under the piles. It was high time he reorganized this place. He hadn't been in the lab in two, three weeks, and hadn't even touched the machine for even longer. Alphys had been so busy lately, and thinking of trying to tackle the damn thing himself was tiring.

"Not over till it's over," he muttered as he sorted the papers into piles on the workbench. "Not over till the timeline is fixed. Fix Gaster, fix the machine, fix the timeline."

There was hope left. There had to be. He just had to hold on tighter, keep it from slipping away. He could afford to be lazy about...well, everything else in his life, but he _had_ to keep his focus on this. Had to stay determined.

Hilarious.

It was his day off, so Sans spent the rest of the day in the lab, organizing the place and throwing himself back into his work. He reread his old notes, jotted down a few equations, sorted through a couple decent ideas. The machine was still as broken as always, but he had been debating whether it would be possible to temporarily repurpose some parts of the machine. There were pieces of it that still worked, systems that could theoretically be redirected. The timeline was fractured, but Sans had never been able to know just _how_ fractured-all he'd had to go on was observation. But there had to be some kind of way to use the time machine to actually analyze the timeline itself. Somewhere in the navigation system should be a ton of data generated and consolidated during its maiden voyage. It was just a matter of getting that data out, and using it to generate new reports of the timeline.

Sans had a few ideas that might work. By the time he started pulling out and reconnecting wires, he happened to glance at a clock. It was later than he'd thought. Papyrus hadn't come home yet-Sans would have heard him tromping around upstairs otherwise. What was today? Papyrus had his sentry shift, and then...was he practicing with Undyne today? They had been at that for awhile now, and Sans was genuinely appreciative of Undyne's efforts. Papyrus had learned all kinds of new strategies and tactics, had developed an all new attack-a secret, he claimed-and he was just generally full of confidence and pep.

Not that he wasn't usually full of confidence and pep, but these days it was even more noticeable. Undyne was good for him.

Sans got to his feet and rubbed at his cervical vertebrae, working out some kinks in his neck. If Papyrus was late, he was probably just hung up at Undyne's. Maybe they'd started a new training regimen. Sans surveyed the lab. It felt like he had actually sort of accomplished something today, so that was good. He could be done for the day. Breaks were always the best part of the day, after all, and he needed to make sure his brother was okay.

He climbed the stairs, tugging on his hoodie as he stepped out into the snow. Once he had the door locked behind him, he dialed Papyrus's number.

No answer. Sans tried Undyne, but it was the same result. They probably just had set their phones down during training. Right?

Sans liked to think that he never crossed the line from protective to overprotective where his brother was concerned. He chuckled a little, remembering a time when Papyrus had _demanded_ that Sans stop walking him to school, because he was a big skeleton now and didn't need his big brother following him everywhere.

Still, big brother instincts were hard to deny. Sans pocketed his phone and teleported, landing at the garbage dump. It was a quick walk from here to Undyne's house. No big deal. He headed that way, teleporting from trash pile to trash pile so he didn't have to get his slippers wet.

Sans could hear them even from the next cave over-the unmistakable sound of Papyrus laughing and Undyne yelling. He grinned to himself. It was a good thing the only people who lived out here were the ghosts. Nothing really seemed to bother those guys.

Surprisingly, though, Papyrus and Undyne weren't outside. The sounds were coming from inside her house. The training dummy out front looked untouched. Strange. Sans knocked on the door. There was no answer, and the yelling didn't stop, so he knocked a bit louder.

The noise stopped, thankfully, and a moment later Undyne flung open the door.

"Oh, it's just Sans." She leaned back and yelled over her shoulder. "Never mind, Papyrus, it's just your brother! Whatcha doing here, punk?"

"Well, I figured you guys were probably having too much fun," he said with a grin and a shrug. "Wouldn't be doing my job if I didn't spoil my little brother's fun every now and then. Gotta keep up appearances and all."

"SANS!" Papyrus emerged from what appeared to be the kitchen, splattered with something red.

"Uh-"

Papyrus was continuing before Sans could even be properly alarmed.

"UNDYNE'S GIVING ME SUPER SECRET SPECIAL TRAINING NOW! SHE IS TEACHING ME HOW TO MAKE SPAGHETTI!"

"Yeah!" Undyne clenched a fist for no reason. "Cooking is basically _exactly_ like warrior training! Diligence! Vigilance! Strategy! It's perfect."

Sans was pretty sure that cooking was just about as far as you could get from warrior training, but then again, what did he know? He chuckled.

"Well hey, that's a great idea. Bro, you gotta make me some someday."

Papyrus grabbed a rag and started wiping his bones clean. Now it made sense-tomato sauce. He crossed the room to join Undyne.

"MY SPAGHETTI WILL BE THE GREATEST IN THE UNDERGROUND! AS GREAT AS ME, WHO IS EXTREMELY GREAT! But...I haven't learned anything past the boiling water part and the smashing tomatoes part, so...I MUST APOLOGIZE, SANS! YOU WILL HAVE TO WAIT BEFORE YOU CAN SAMPLE MY AMAZING SPAGHETTI! But...you certainly won't have to wait long!"

Smashing tomatoes. Maybe he was wrong. Maybe cooking really _was_ exactly like warrior training-at least when taught by Undyne.

"Ah, well. I'm sure it'll be worth the wait. Anyway." Sans leaned against the doorframe. "You guys gonna be at it for much longer?"

"Oh, jeez." Undyne smacked her forehead. "I totally lost track of time. I got so into describing methods for boiling water I wasn't paying attention!"

"WOWIE! Even the GREAT PAPYRUS didn't notice how late it was! Sorry, brother."

"Nah, don't worry. I'm not _upsetti."_

"Ugh," said Papyrus and Undyne at the same time. Sans laughed.

"But nah. Just a call next time or something. That thing about spoiling the fun was mostly a joke."

"A Royal Guard must be PUNCTUAL and keep close track of time!" Papyrus raised a solemn hand, as if he was about to swear an oath. "I WILL NOT LET IT HAPPEN AGAIN!"

"Pfft, yeah, you're gonna make an amazing Guard someday!" Undyne said, punching Papyrus lightly in the humerus. Papyrus beamed and surreptitiously rubbed at the spot.

"Guess I'll head on home, then," Sans said with a languid shrug. "Got important naps to attend to."

"SANS! DON'T GO TO SLEEP!"

"Really? You came all the way out here and now you're just gonna leave?"

Sans jerked a thumb over his shoulder. "Nah, I know a good shortcut. Gets me home real fast. Wouldn't want to get in the way of the pasta-making."

"Jeez, fine! Go take a nap, you lazy weirdo. ...Actually!" Undyne's eyes widened abruptly and she dropped a fist into her open palm. "Wait, before you go! Had something I needed to ask you. I almost forgot."

She braced a hand against the doorframe and leaned forward a bit, looming over Sans just slightly. It was kind of amazing how she could go from Papyrus's ridiculous friend to the Captain of the Royal Guard so quickly.

"Okay?"

"Me and Paps were talking about you earlier."

"Only good things, I hope."

"He said you only have 1 HP. Is that true?"

Sans's eyelights flicked past Undyne to Papyrus. His brother immediately looked sheepish, clasping his hands together in front of his chest.

Papyrus was supposed to know better. It wasn't like it was a secret, exactly. It wasn't the sort of secret you could keep for very long. You had to put your HP down on all kinds of forms, anything that involved legality or liability. Sans's HP had already come up with the dogs in Snowdin. Sans loved the guys, but dogs tended to play rough and liked to swing weapons around a lot. Not exactly the safest environment for someone like Sans. Now they were a bit more careful, but they were all still in that stage that Sans hated, the stage where they were cautious and apologetic and sympathetic and constantly asking about Sans's health. And that was one of several reasons why Sans avoided telling people.

Never mind that just having 1 HP was tiring on its own, but the questions, the explanations, the pitying or disdainful or puzzled looks on people's faces just made everything _exhausting._

Papyrus wasn't one to just randomly tell Undyne. It must have simply come up. The fact that he had told her outright meant that he trusted her, meant that they really were friends. Sans wasn't angry, not really, but…

That look on Undyne's face was also exhausting.

"Kind of a weird thing to talk about," he said with a shrug, eyelights moving back to Undyne. "But yeah, it's true. "

"So how can you be a sentry with just 1 HP?"

"Ah, Undyne, that wasn't-I thought when we were talking earlier that you meant…"

"Hold on, Paps, I got a point. I just need to get to it! Well, Sans?"

Sans hadn't felt this scrutinized in a long time. He couldn't help but be reminded of his old boss in the Core, staring at him from across the desk, mockery in his tinny voice as he asked about Sans's 1 HP. Or...before that, Gaster's quiet horror when he realized that not only was Sans weaker than he had let on, he had also lied to get a job that involved dangerous science.

Sans shrugged again.

"I mean, they hired me in spite of it, right? The dog who interviewed me made it sound like it wasn't a big deal."

"Listen, hiring the sentries is totally independent of me, it's like a sub-department or something. If I'd known about it, I would have made sure they asked more questions! I mean, sentry work isn't as dangerous as being in the Guard, but it's still dangerous. You guys are the front line against the human threat, like...like scouts, basically!"

Sans stared at a spot in the vicinity of Undyne's abdomen.

"Captain, if I'm fired, you can just tell me."

Maybe he could get odd jobs in the Core again, in a different sector. Or he could...he could wash dishes at Grillby's or something. Grillby was a great guy, he'd totally be willing to hire on his best customer. Between Sans's three separate sentry stations he'd been able to set a bunch of money aside, so even if he was unemployed for awhile, that...that was fine. They'd still be able to pay rent for awhile. Long enough to figure something out.

They weren't going to end up on the streets. Never again. Sans wouldn't allow it. At the very least, Sans was going to make sure his brother kept a roof over his head for the rest of his natural life.

"NOW WAIT JUST A SECOND!" Papyrus crossed to the door in two strides. "Undyne, that wasn't why I mentioned it earlier! You can't just-"

"Okay, jeez, both of you just slow down!" Undyne raised both hands. "No one's getting fired, alright?"

Sans stared up at her, resisting the urge to ask what the _point_ was, then.

"Look, I figure if you've gone this long with just 1 HP, you've gotta be able to take care of yourself. But as the Captain of the Guard, I have to make sure everyone in the ranks is up to snuff, you know? And I've never actually seen you use magic or anything. Heck, if I had the time, I'd be hiring and testing and training all the sentries myself! I get this is a delicate subject, even, but I didn't get to where I am by being delicate! So I just need to be sure." She pointed a finger at Sans. _"Are you_ okay as a sentry? Are you gonna be able to handle yourself in a fight?"

Sans stuffed his hands in his pockets and sighed. This was annoying, but he always found himself preferring Undyne's bluntness to people who walked on eggshells around him.

"Sans is GREAT at magic!" Papyrus said, relaxing a bit now that it didn't seem like his brother was about to be fired. "Not as great as the GREAT PAPYRUS, of course! But still! VERY GREAT!"

Sans couldn't help a bit of a chuckle.

"I know, Paps, but I'm asking Sans, not you," Undyne said firmly, patting Papyrus's shoulder.

"I mean, I actually like being a sentry," Sans said finally. "Even at three whole stations. It's kinda nice. You meet all kinds of weird people. Hear all kinds of fun gossip and news. It's a nice gig. I've never really had a real job until now."

It wasn't even technically a lie.

"And I think I've been doing pretty good so far. I submit all my reports on time. I know pretty much all the other sentries. I've never exactly been in a situation where I had to face a human, but I know all the protocols. So...bottom line is, yeah. I'm okay as a sentry. I figure if anyone had a problem with me I would have heard about it before now."

He could understand Undyne's reasons for bringing all this up, but that didn't make it any less irritating. Even back when he was younger, back when he still couldn't really use magic at all, he had gotten by just fine. Summoning bullets wasn't everything. He had lived a relatively normal life, aside from all the general mayhem of the last few years.

"What about magic?" Undyne asked, tilting her head. "You can use magic, right? Can you fight?"

He shrugged. "Sure, if I need to."

She peered down at him through one bright yellow eye, drumming her claws against the front door. In the background, Papyrus was gripping his gloved hands, still looking a bit nervous.

"Prove it."

"...Sorry?"

She grinned and clenched both fists in sheer passion.

"Spar with me! Me and Papyrus have been sparring all day, but I'm good for another round!"

"UNDYNE! THAT IS AN EXCELLENT IDEA!" Papyrus said, brightening immediately. "THERE IS NO BETTER WAY FOR FRIENDS TO GET TO KNOW EACH OTHER THAN WITH A FRIENDLY BATTLE, FRIEND-STYLE! THE GREAT PAPYRUS APPROVES! SO LONG AS YOU ARE CAREFUL! Very careful."

"Uhhhh. Yeah, no," Sans said, giving Undyne a bemused look. "I'm not gonna fight you right now."

"What! Why not?"

"It's late, and I'm not a big fan of fighting. Fighting is basically work, and I'm done with work for the day. I'm due for a real long break at Grillby's."

"You need to prove to me that you can fight!"

Sans gave a languid shrug. "Ehh. I'll take a rain check."

Undyne glared at him. "...Fine, then! Tomorrow."

"Aw, jeez. I'm booked solid tomorrow. Three whole stations, yanno? I'm a pretty busy guy. Plus the new MTT Hotel is looking for talent. Not that I'm 'talent,' but I'm the next best thing." He winked at her, which made her visibly fume. He wouldn't have been surprised if smoke started pouring out of her ears.

"THEN SOMETIME THIS WEEK!" She thrust a claw at him. "I'll ambush you! Keep you on your toes!"

No one could dodge like Sans could. Undyne was a very noticeable presence-it wouldn't be at all difficult to avoid her. He had thousands of excuses for randomly disappearing or just generally being "busy" whenever Undyne came looking.

He wondered how long he could hold her off. This might actually be fun.

"Then I guess I'll have to keep an _eyesocket_ out," he said, turning to go. "Have fun with the rest of your training, bro. See you at home."

"NYEH! When I get home, I can help you prepare for your EXCITING AMBUSH!"

Undyne cupped both hands around her mouth to call after him. "I'M GONNA GET WHEN YOU LEAST EXPECT IT, SKELETON!"

Sans chuckled, rounded a corner, and disappeared. He was still laughing when he landed back at home.

He wouldn't be able to avoid Undyne forever, but that was fine. Stringing her along and annoying the hell out of her would be hilarious in the meantime. And when it did come to a fight, she would at least know to be careful. Even if she wasn't, he could dodge anything she threw at him. He had a much better handle on his magic these days. It still got away from him from time to time, but he should be fine for one "friendly battle," as Papyrus had put it. When she saw what he could do, she'd leave him alone.

This was going to be an interesting week.

* * *

Undyne was true to her word. The following day, Sans was reading a car magazine at his stand at the border of Waterfall and Hotland when Undyne appeared. She'd actually been lurking nearby for several minutes and Sans had watched her out of the corner of his eyesocket the entire time. Finally, she approached him and pushed down the top edge of the magazine.

"You don't look like you're _working,_ Sans."

He glanced up at her. She was in her full Royal Guard armor and was sweating from the heat. She looked irritated and uncomfortable.

"Oh, I'm working really hard," he said, looking back at his magazine. "You never know when a human might drive a car into the Underground."

"If you have spare time to read magazines then you have spare time to spar with me!"

"Sorry, can't. I have to head to the Waterfall station in five minutes."

Technically it was more like an hour, but Sans had a great work ethic and loved to arrive early to his job. Get a headstart on his work and all that completely untrue stuff.

 _"How_ do you have three stations? How do you get to them all?"

"Shortcuts."

"You keep saying that! Since when are there shortcuts in the Underground? Anyway, we could spar on your way to your other station!"

"And show up to work all disheveled?" He shook his head and closed his magazine. "Undyne, I'm surprised at you. I thought you valued professionalism."

Undyne made a vaguely roaring sound.

"FINE! LATER, THEN! We're gonna spar, Sans, just you wait!"

"Okay." Sans got up to close down his station.

"Also, I'm gonna follow you. I'm curious about this 'shortcut.' What if a human decides to use it?"

"Nah, a human wouldn't be able to use it," Sans said, shrugging and heading in the direction of Waterfall. "Don't think a tall fish monster will be able to, either. It only really works for little skeletal guys."

He could hear Undyne's metallic footsteps following him.

"Well, at least tell me where it is!"

"It's right over here," Sans said, rounding a corner. He teleported the instant he was out of sight, landing in a crevice near his Waterfall station. No one was around. He started laughing as he set up his station and took a seat. Man, this was exactly as hilarious as he had been hoping it would be.

Undyne didn't appear for the entire rest of the day. Sans took the opportunity to finish reading his car magazine and pull a few water sausages out of the marsh. He'd been curious for awhile now about whether they were edible or not. They looked so much like hotdogs growing right out of the ground.

There really wasn't much to do as a sentry. It was easy to get this bored.

Papyrus was out again that evening training with Unydne, so Sans borrowed the kitchen. Papyrus would probably look at him funny if he caught him frying up water sausages, and Sans couldn't think of a single logical explanation beyond "they look tasty." Sticking them in a hotdog bun and slathering them with ketchup made them look exactly like a hotdog.

And as it turned out, they tasted pretty good. Sort of like a vegetarian hotdog. Sans was pretty sure that, technically, no one in the Underground had ever had a real hotdog anyway. It wasn't exactly easy to get meat products down here, except for fish. Even the amazing burgers that Grillby served weren't technically meat, though they tasted like it. Monster food could taste like anything you wanted. That was the beauty of magic.

Sans considered the remains of his water sausages. He still had one left over.

Maybe this was the start of something interesting.

The next day, Undyne was waiting for Sans at his station in Waterfall. As soon as he spotted her, he shrugged and teleported to his station in the middle of Hotland instead. It was more heavily trafficked than that part of Waterfall anyway, and there was something that Sans wanted to try. He arrived at his Hotland station armed with a bag of fried water sausages, hotdog buns and condiments.

Once there he placed a small sigh that said "Hotdogs 30G" on the front, took a seat, and folded his hands on the counter. Now all he needed was a customer.

It took awhile, but Sans was a patient monster. There was a handful of sentry tasks to do and at least one patrol he should probably take in the meantime. He watched several monsters walk by on their way to the Core and give his stand a doubletake. A couple people looked like they wanted to approach but were clearly in a hurry.

Finally, though, a tiny Vulkin padded up to his stand, steam rising from the top of its head in puffs. Sans braced his hands on the counter and leaned over so he could see the Vulkin properly. There weren't all that many monsters that were shorter than he was. Moldsmals, mostly.

"Hey there. Interested in a hotdog? It's just 30G."

The Vulkin stared up at him with wide eyes, blushing slightly.

"Um, well...I had a question? Um...what's a hotdog?"

"It's like a food that humans eat. It's a sausage that you put in some bread and top with condiments. Like ketchup."

"Ohhhh...like a water sausage?"

"Exactly like a water sausage. Here, I have an idea." Sans picked up one of the hotdogs he had prepared and got up, crossing to the other side of his stand. "Since you're my very first customer, how about I give you one on the house? And if it's any good, you can tell people about it."

The Vulkin's blush deepened.

"Uwa! For free? Are you sure?"

"Sure I'm sure."

Vulkins didn't have arms, so Sans settled for placing the hotdog on top of its head, careful to avoid the lava. The Vulkin beamed at him.

"Thank you, mister! I have to go to work, but I'll come back and tell you how it was! It's a promise!"

"Cool." Sans winked at the Vulkin. "I'd really appreciate it."

"I had another quick question...how come there's snow on the roof of your stand?"

Sans glanced up at it.

"Eh." He shrugged. "Too lazy to scrape it off."

"Oh. Well, thank you for the hot...dog? Cat?"

"Just hotdogs for now. Maybe I'll start selling hotcats if business takes off." Sans couldn't help chuckling at the idea. He was pretty sure that hotcats didn't exist.

The Vulkin scampered away and Sans sat back down. For his first ever job as a salesman, that had gone pretty well. Maybe he could give away the rest of the hotdogs for free as well. Opening day sale, or something. That would get his foot in the door, so to speak, and people would come back for more if they liked them.

Sans only had ten more hotdogs, so it wasn't too difficult to hand the rest out to people over the rest of his shift. A Pyrope even came back for seconds and actually paid for the last one. Sans went home with 30 extra G in his pocket and a bit of a spring in his step. Capitalism was turning out to be a lot of fun.

Undyne was waiting for him at his front door when he got back. Papyrus was there as well, apparently chatting with her about spaghetti techniques.

"There you are!" She jabbed a finger in his direction. "You weren't at your station! Did you skip out of work?!"

"SANS! I TOLD YOU TO STOP DOING THAT!"

"Nah, I just took a shift at my Hotland station instead," Sans said with a casual shrug.

"I checked your Hotland station!"

"My _other_ Hotland station." Sans winked at Undyne, which only made her more angry. "It's closer to the Core."

"Ugh, whatever, fine." Undyne rubbed at her forehead as if she had a headache. "Well, you're back now, and I have some time before I need to go turn in my daily reports to Asgore, so! We're going to spar now!"

"Ah, man. I'm sorry. I'm _bone_ tired from that shift. Hotland always wears me out, yanno?"

"Hotland wears _everybody_ out," Papyrus said in a disgusted tone.

Undyne glared daggers at Sans. Or at least dagger.

"You're a real slippery one, aren't you? FINE! Tomorrow."

"Sure." He gave her a thumbs up. "It's a date."

* * *

This went on for several more days. Every time Sans spotted Undyne lurking at one of his stations, he simply headed to a different one. Every time he saw her keeping her eye on his route to or from his station, he simply teleported. Every time she managed to actually catch him, he had a perfectly legitimate excuse for why he couldn't spar right then. He was too tired, or he was late to work, or he had to help one of the Snowdin dogs with something. Every time, Undyne would glare and fume and tell him, _soon._

In the meantime, Sans set about collecting more water sausages, and also managed to get a small grill that he could easily hide behind his stand. He started stocking all of his stands with condiments, just in case. The hotdog business was very slow at first, with just a small handful of regulars, including the Vulkin and the Pyrope from the first day. Word began to spread, however, and every day saw a couple more customers than the last. It turned out that his stand in Hotland was perfectly located, as a lot of monsters were in that exact area during their lunch breaks. There weren't that many businesses in Hotland at all aside from the Core and the Royal Scientist's Laboratory, so the options for food were sorely limited. Water sausages, for all that they were just a weird plant, were a far cry better than the food in the Core's cafeteria.

It was nice. Fun, even. It occupied his days, at least, during times when he wasn't doing actual sentry work or jotting down notes and equations on the sly. Dodging Undyne and seeing the look on her face each time was just the icing on the monster cake.

Even Alphys came out to his hotdog stand one day when word finally got to her. It was the first time he'd seen her in about a month. She looked exhausted, and her labcoat was slightly rumpled, as if she'd slept in it.

"Well, hey. _The_ Royal Scientist, gracing my humble hotdog joint."

Alphys chuckled and gave him a tired smile. "I can't believe the Guards let you do this. Aren't you s-supposed to be watching for humans or something?"

"What they don't know can't hurt them."

"Pfft." She paid for her hotdog and he handed her one. "Leave it to you to do something this weird and funny. ...Hey, this is actually pretty good."

"I like finding loopholes. Seriously, though, it's good to see you. How have you been? You seem, uh…"

"Like a mess?" she offered dryly.

"I was gonna say tired."

She shrugged. "It's just, um. J-Job stress, you know? The usual."

Things were like this now. She had been telling him fewer and fewer details about her job or the nature of her work. He was pretty sure that Alphys and Asgore himself were the only ones who knew what she was working on.

"What about you?"

"Oh. Same-the usual."

The usual meaning he still was getting nowhere with the machine, and it still felt like he was getting nowhere with Gaster. The dreams still happened with some regularity, and though Gaster had calmed down over the past year, they were still rather harrowing. Gaster was a far cry from actual coherency.

"Heh." She finished off her hotdog and gave him a sad look. "Look at us both."

"...Heh."

There was an awkward silence. Sans fiddled with a bottle of ketchup, not looking at Alphys.

"Well, I gotta get back. Think I left the Bunsen burners on, h-heh."

"Hey, do you wanna...we could maybe hang out this weekend? I've, uh, got both days free, and...we don't have to do, yanno, any real work, but uh. We could watch anime or something...like before?"

"Oh….man, that sounds great?" Alphys wrung her hands. "That s-sounds really great, but um, I'm actually starting a really big experiment this weekend. I'm building-um, s-something. It's gonna take my full attention for the next two, three weeks."

"Oh, okay." Sans was careful not to sound at all disappointed. He gave her an encouraging smile instead. "Well, yanno, let me know. Maybe in a few weeks or something."

"Yeah! Yeah. Maybe. Um, I'll see you, Sans."

With that, she was gone. Sans waited until she was out of sight to sigh to himself. He got to his feet and put out a sign that said "Back in 5." Practicing magic for a bit usually made him feel a little better. Or at least tired enough to not worry about anything.

* * *

Less than a week had gone by before Undyne finally caught him. He was on his way out the door and found Undyne waiting on the doorstep. It was mildly startling.

"Jeez. You know, I'd think the Captain of the Guard has more important things to do than wait around so she can fight a random skeleton."

She gave him a withering look.

"I'm waiting for you _and_ your brother, dummy. He's got all day training today! But that doesn't start for an hour-the perfect amount of time for a good round of sparring!"

"Sorry, no can do," he said, giving her an apologetic shrug. "I've got two shifts today."

"Actually." She paused and showed every single one of her teeth in what he hoped was a grin. "You don't."

"I don't."

"I had the sentries give you the day off! Since you've been working _so hard_ the past week."

He raised a brow ridge at her. "Wow. And what if a human happens by while I'm away? Wasn't the whole point of wanting to fight me because you were worried about security?"

"Oh, I thought of that. I'm not stupid, Sans. I didn't always cover all my bases!" She folded her arms. "Best Dog and Plasmo agreed to cover your shifts."

He winced. "Man, you didn't send Best Dog out to Hotland, did you? She hasn't been feeling well lately, and the dogs never do too well in that heat."

"No, jeez, she's covering the Waterfall shift." She made a face. "I'm not a _human._ Plasmo's a fire elemental, so it makes more sense that he's in Hotland. Honestly, who put that poor guy at a station in Waterfall, anyway?"

"Yeah, he's been asking for a transfer for awhile."

She tapped her chin. "I bet I could streamline that for him. It's important that our sentries are being utilized where they're best suited, just like the Guards. I'm gonna have a talk with the head of the sentries, see if I can-HEY!"

The shout was so sudden that Sans flinched.

"YOU'RE DOING IT AGAIN!" She put her hands on her hips and leaned menacingly toward Sans. "YOU'RE STALLING."

"Oh. Heh." Sans pulled his hands out of his pockets. "Yeah, you got me. Guess there's no _fin_ I can say to get me out of it this time, huh?"

Undyne's grin was wild. "Not anymore. I told you I'd get you. Now I'm finally gonna see what you're made of!"

"Calcium and magic, mostly." Sans heaved a sigh. No avoiding it now.

Undyne waved her hand and summoned a spear made of solid magic out of thin air. It was electric blue and almost as long as she was tall. Sans couldn't help an automatic step backward. It was impressive. Not many people could use their magic to create actual weapons. Most monsters just relied on their bullet patterns.

"Uh. We're not gonna fight here, are we? Cause I'd rather not trash the street."

"No way! There's a good spot down that way, by the river." She gestured in that direction, toward a low section of the road that led to Waterfall. The area tended to get misty at night, though it had mostly burnt away by now. It would still be a bit difficult to see one's footing.

"You know...what if I just throw some bullets at some trees or something? Instead of us actually fighting."

"Trees aren't going to fight back." She pointed the spear at him, which made him take another step back. She seemed to notice, because she lowered the spear a moment later, point toward the ground.

"This isn't really a question of whether you can use _magic_ so much as whether you can defend yourself. So! Enough stalling!"

She jerked a thumb toward the patch of road and mist. Sans sighed again and trudged forward, feeling a bit like a monster condemned. He doubted Undyne would accidentally kill him, but there were very, very few monsters that he actually trusted to use magic on him. Monsters weren't always all that careful about their bullet patterns, or about where their bullets were heading. Undyne was the Captain of the Guard, so she had to have excellent control over her magic, but she was also excitable and a bit reckless.

And she wasn't Papyrus. Papyrus was the only monster Sans had ever met who could _stop_ his bullets on a dime. He had such perfect control over his magic that he made every other monster in the Underground look downright sloppy.

Sans situated himself with his back to the road, affording himself the largest possible area for dodging. Undyne put herself against the river across from him. She spun the spear in her hands with alarming expertise and pointed it at him again.

"You ready, skeleton?"

He pretended to stifle a yawn. "Ready as I'll ever be."

"Good. CAUSE HERE I COME!"

She charged. She was an awful lot faster than he expected, even with her armor. Sans darted backward as she made a wide sweeping motion with the spear. The blade crackled with magic as it sailed past.

Well, if it was a proper fight she wanted…

The most basic thing they ever taught you about monster battles was range. The vast majority of monsters relied heavily on range, since that was the whole point of bullets. But while a properly formed bullet pattern was important for the more nuanced parts of monster society, you needed all kinds of different patterns and tactics for an actual fight. And range was an important part of that. If you were a Woshua who relied on wide-range spiralling bullet patterns, then you were going to have a hard time against, say, an Icecap who was better equipped for getting up close and personal.

Sans was much better at long range, and Undyne was very much up in his business. She had already corrected, surging forward again with a sweep in the opposite direction. Sans dodged backward and to the side, and as soon as the blade passed him he reached out a hand and turned Undyne's soul blue.

 _Ding._

Undyne looked momentarily aghast, but Sans didn't waste a second. He shoved with his magic, sending Undyne sailing backward. She almost toppled, but bent forward and planted her spear hard into the snow to keep herself upright. Sans released her and stuffed his hands in his pockets, grinning widely. She glared at him over the butt of the spear, hair hanging in her face.

"Always wondered why people don't lead with one of their better attacks," he mused. "Or even just their strongest attack, yanno? End the fight quickly. I'm a huge fan of ending things quickly."

Undyne stood up straight.

"Yeah, so I've noticed. Alright, if THAT'S HOW YOU WANT TO PLAY!"

She threw the spear. Sans's eyelights flicked up to it as it sailed directly toward his ribcage. He dodged right and the spear planted halfway into the ground, fizzling out a split second later. Undyne created a second spear almost instantly and launched it at him again. He dodged left this time.

As soon as his feet were planted, he answered with a wave of bones from the ground. She didn't dodge-most monsters didn't, really. She jumped, but the wave wasn't uniform-it moved up and down, like a normal wave should. A few bones at the peak slammed into her shins. She landed with a snarl and summoned another spear, shattering the remainder of the wave with a single sweep.

"That barely even hurt!" She raised her free hand and summoned a stream of bullets that looked like miniature spears. All of them shot straight toward him like arrows, flashing red the closer they came. Sans dodged and she followed him, forcing him into an almost-run as spears zipped past him.

"Do your attacks only do…" Undyne frowned abruptly as her stream of spears ended. She looked down at her legs. The areas where the bones had struck were glowing very faint pink.

"Oh, that's weird. What the hell did you do?!"

"Heh." He sent a double wave of bones at her, this one uniform in height, coming at her from above and below. She had to jump very carefully to avoid them. "Just a bit of karmic retribution for making me dodge you all week."

She avoided almost every bone, tripping over the last one. She barely stumbled.

"Yeah, you're real good at dodging!" She threw another spear at him, even faster this time, but a few quick steps backward and the spear planted harmlessly into the snow a foot in front of him.

"Ugh, you're so annoying!" Undyne ducked as he threw several bones toward her head. "Stand still and face me head on!"

"Not really my style," he said, a bit breathless as he dodged another row of spear bullets from her. Some of them were colored gold; as soon as he dodged them, they changed direction and came at him from a different angle, forcing him to dodge a second time. "Hey, you know about blue attacks, right? I sure hope so."

The next wave of bones were alternating between monster white and light blue. _Cyan_. He could almost hear the doctor correcting him. Undyne got mixed up on a few of them, standing still for a light blue bone and then tripping over the next white one. This one knocked her down. She was back on her feet so fast it was like the ground had simply repelled her.

"How can you fight properly if all you do is dodge?" She threw a spear at him, then followed it up with several golden spear bullets. Sans gritted his teeth, ducking the spear and nearly cartwheeling to dodge the bullets.

"You need to defend sometime!"

"Nah." He was breathing hard now. His magic was still overpowering, and injecting KR into some of the bones took a lot out of him. Each bone only did one point of damage, so the KR was a nice follow up to keep people on their toes, slowly draining their HP over time. He hadn't yet figured out how to fill all the bones with KR. It seemed virtually impossible.

He tried a different tactic, sending several long femurs at her from both sides, allowing her virtually no space to avoid them. She would _have_ to dodge-see how _she_ liked it.

Most monsters just weren't used to dodging, though. Almost every bone struck her hard, one of them even shattering on impact and sending her spinning. She almost went down again, but planted another spear to stay up. For all that, she didn't even look winded, and even at a glance it was clear she hadn't lost that much HP.

"What are you going to do if you _can't_ dodge?!" she demanded, sending another flurry of spear bullets at him, these ones alternating between the flashing red and the gold.

"Die, probably," he muttered, too quiet for Undyne to hear, too busy dodging. Her attacks were becoming more complicated, and the gold ones were very tricky. One whizzed by dangerously close to his skull.

He dodged the final one and lost his balance for a moment, hitting the snow with one hand before shoving himself back up. His left eyesocket was starting to hurt and his magic was starting to feel erratic. Throwing bone patterns at trees really was very different from fighting an actual person.

He wasn't going to lose control. If he felt it escaping, he'd just forfeit.

It wasn't like he was going to win, anyway.

As soon as he had his balance back, he raised a hand and turned Undyne blue again. He tossed her upward, and the effort made the pain in his left eyesocket worse. He couldn't let the eye trigger-she'd ask too many questions, ones he either wouldn't have answers to or didn't _want_ to answer. He released her when she was about ten feet in the air, letting her drop. Several rows of short bones sprang up out of the ground like flowers to greet her.

She landed hard, breaking several of the bone bullets and letting out a grunt of pain. But she was back on her feet again in an instant, as if nothing had happened. She was even grinning. She was having _fun._

"Alright, then, if you love soul magic so much, try _this_ on for size!"

Undyne made a sweeping motion with her spear. Sans braced himself, ready to dodge.

 _Ding._

Sans froze.

Something clamped down on him, on every inch of him, a familiar heaviness.

Undyne put her free hand on her hip and laughed.

"Ha! Now what're you gonna do, huh? You can't dodge if you can't move!"

With an effort, he shifted his eyelights downward. There was a small green glow at his chest.

"Oh," he heard himself say.

"Now you _have_ to defend! You bet…r brac…"

Undyne's voice faded out slowly, as if she was disappearing into a tunnel. Sans's vision went funny. Everything went dark at the edges, Undyne became little more than a shadow in the distance. It was hot. He was sweating. Sweating and shivering.

He was in the Core and Gaster was standing over him one hand outstretched and he was green he was green and he couldn't move and the Core shook and the void churned away beneath them like it was hungry like it was starving and Gaster stepped forward and that thing appeared at his side like a loyal pet a Gaster Blaster and he was speaking or Undyne was speaking-

 _You can't dodge if you can't move_

 _But at the end of the day you are still a failure_

 _What's going on here_

 _What did you think I saw when I looked at you_

 _What's wrong with him_

 _Nothing but a science project_

It felt like he was floating. Or sinking. A thousand miles beneath an endless ocean, the pressure crushing him, grinding his bones to powder, to dust. He was falling, he had to be, falling into the darkness, no machine to protect him this time, the machine was broken after all, and it was all happening again, the Core tearing to pieces around them, the darkness swallowing him up, coiling around his bones, curling _into_ his bones, and he thought he felt himself breathing too fast, too fast, before he shattered.

Someone was speaking nearby, or from very far away, the same word over and over, but he couldn't make it out. Everything was green. Heavy. The Blaster would fire any second now, a spear would slam into his sternum, and he couldn't move and he couldn't move and he _couldn't move._

His skull was ringing.

He felt himself shake. Or. No. Someone was shaking him. There was another heaviness, but different. Softer. Something wrapped around him. Rumbling sounds from close by. Close by. Close…

Snow against his knees. Snow between his tibias and fibulas. He was on his knees. When had that happened? Mist around him. The trickle of water nearby. Someone holding him.

Papyrus holding him.

He sucked in a breath. Shifted his arms. They felt like lead, but they were moving. Papyrus's grip tightened.

"Sans?"

He pulled back slightly, just enough so that he could look Sans in the face. Sans blinked at him. Relief flooded Papyrus's features. He looked close to tears.

"There you are. _There you are."_

He pulled Sans back into a tight hug. Sans could move. He could move his hands. He raised them slowly, wrapped his arms around Papyrus, fingers curling into his shirt, holding on as tight as he possibly could. Something was still rattling. That had to be him. He was shaking. Trembling like a frightened child.

"He's okay now," Papyrus said, a bit louder. "It's okay."

"Oh, thank god." Undyne's voice from nearby. "Sans, I'm-can he hear me? Sans, can you hear me?"

"Mm." Sans's voice still sounded distant, like it was coming from someone else.

"Asgore's beard." Undyne sounded breathless. Winded, finally. Heh. Funny. He'd finally given her a workout. "Sans, I'm so...I'm _so_ sorry. I got caught up in it all and...I'm sorry. It'll _never_ happen again."

"I don't…" Sans's voice was muffled against Papyrus's chest. He lifted his head slightly. "What happened?"

"Brother, do you not...remember?"

Sans pulled back from him and scrubbed at his eyesockets. Papyrus tried to hold onto him but Sans gently pushed his hands away. He felt like someone had stuffed his skull full of cotton, but he knew he had to get this under control. Had to get _himself_ under control. Something had happened, something bad, and he had to get ahead of this before the questions started.

"No, uh, I mean-me and Undyne were sparring?" He stood, even though his legs were shaking. Papyrus reached out to steady him, and when Sans tried to push his hands away again, Papyrus didn't let go.

"Uh, I totally had her on the ropes, though. Right?" He put on a grin, looking to Undyne for help. She was standing stock-still a few feet away, her spear gone.

Her expression was…

She was _pitying_ him.

"I turned your soul green," she said, her voice uncharacteristically soft. "And you just-kind of froze. Like...green makes it so you can't move, but not like _that._ You started shaking. But I didn't, uh...I didn't realize what was happening, and…"

She looked over at Papyrus, contrite.

"It's alright, Undyne!" Papyrus said, smiling again, some of the boisterous cheer coming back to his voice. "You didn't know what was happening! Not everyone can react as quickly as the Great Papyrus when it comes to Sans's safety! I am a VERY great brother, after all!"

Sans stared at Papyrus. There were a few scorch marks on his shirt and arm bones that Sans hadn't noticed until now.

He felt like his soul was crumbling.

"You took a hit for me?"

Papyrus hadn't needed to do that since…hell, probably since grade school. Since they were both babybones.

His brother puffed out his chest.

"No need to worry, brother! Or thank me! It didn't even hurt! Undyne stopped very quickly, because she is ALMOST as great as me!"

"Papyrus, this is serious," Undyne said, a stern note creeping into her voice. "Sans-"

"WELL, serious or not! We should continue this! Not here! Let's go indoors where it's warm and there is no snow and where Sans can sit down!"

"Bro, I'm-"

Papyrus scooped him up before Sans could even protest, gathering him into his arms. Sans sighed and let it happen. Normally having Papyrus carry him was the best thing in the world, but right now….

"I freaked out, didn't I?" Sans's voice was quiet, almost a whisper.

"Shush."

"I'm sorry."

"Hush."

"Listen, I'm fine now. You don't need to fuss. It's not a big deal. Probably just some, I dunno, maybe my soul just doesn't react well to soul magic? It's not-"

 _"Shush."_

Sans went quiet, tipping his forehead against Papyrus's shoulder. He wanted nothing more than to crawl into his bed and disappear for a few days.

Papyrus carried him indoors and Undyne trailed behind, her face unreadable. Once inside, Papyrus set Sans down on the couch. When Sans tried to stand, Papyrus gently pushed him back down. Sans resigned himself to the couch. There was no arguing with Papyrus when he got like this.

Papyrus went to the kitchen to make tea while Sans dusted snow off his legs and stared into the middle distance. Undyne hovered in the entryway, clearly feeling guilty and out of place. Sans tried to process what had happened. They were fighting, and then he was green, and then…

It was like his mind had simply…stopped working. It was like the worst of his nightmares. Unable to move, unable to think. It had almost felt like he was back in the Core. Like he was staring down the throat of a Gaster Blaster. Like Gaster was pinning him to the machine, digging his thumbs into Sans's wrists, and it had _hurt,_ but being thrown had hurt worse, and passing through the void, Gaster's magic forcing its way into his soul, had hurt worst of all.

"Sans?" Undyne's voice cut through his thoughts

He flinched and blinked, still not looking at her. He was doing it again. He was going away again.

"Are you _really_ okay?" she asked, voice low so Papyrus wouldn't overhear.

"I'm fine," he said in the same tone. "What actually...happened? After you turned me green. I mean, uh. Heh, I know _blue's_ more my color, but-"

"TEA FIRST!" Papyrus said, emerging from the kitchen with three steaming mugs. He set one on the coffee table in front of Sans. "Drink first. Then you can talk."

"Thanks, Papyrus," Undyne said as he handed her a mug. "But I, uh…maybe I should go. I feel like I'm intruding."

"It's fine," Sans said, still not looking at anything or anyone. Papyrus sat down beside him. "I said I'm fine. You can stay. You still need to assess whether I'm good enough to keep being a sentry, right?"

Obviously he wasn't. They all had to be thinking the same thing. Sans's eyelights settled on his mug of tea.

"Of course you are." Undyne said it as if it wasn't even a question.

He looked over at her finally. She still had that odd look on her face.

"I mean, you fought really well. I really didn't expect you to, honestly? But those were some pretty creative tactics. Especially combining both types of blue magic. I don't think anyone but Papyrus can do that."

"Oh."

He looked back at his tea. More pity. Great. He picked up the mug and took a sip, then nearly choked. It wasn't even tea. It was hot water mixed with a bit of ketchup.

Just like Papyrus used to make, back when Sans was too weak to process normal monster food, back when the only thing they had in the house that would dissolve in water and go down easy was ketchup.

Sans set the mug back down.

"Can someone. Please just tell me what happened."

Papyrus tapped the rim of Sans's mug. _"Drink."_

Sans felt like throwing the mug across the room, but instead he picked it up again and downed half of it in one gulp.

"You froze up," Undyne said. She hadn't moved from the entryway. "And I almost-I could have killed you, but Papyrus jumped in the way. When your soul is green, you're supposed be able to summon a sort of force field, like a shield to defend with, but you…didn't."

"How did…you even get there that fast, bro?"

"I came out to watch. I'd been watching for a little while! Sans, we don't need to talk about this now. You should-"

"I drank the stupid tea, can someone _please just tell me what happened."_

Sans hated himself for the frustration and frantic desperation in his voice. He drank the rest of the tea so he wouldn't have to look at either of them, hands starting to shake again. For awhile, neither of them spoke.

"I let you go the second I realized what was happening," Undyne said at last. "And then you just sort of…collapsed. You wouldn't move or…me and Papyrus were trying to talk to you, but all you would say was 'stop, stop', over and over. Real quiet. Even after I'd released the spell."

"I held onto you and eventually you came back," Papyrus added, folding his hands tightly in his lap.

"Wait, how…how long was I like that?"

There was a silence. He glanced up to see Papyrus and Undyne exchanging a look.

"Like...five minutes," Undyne said after a moment.

Five _minutes?_ It had felt like…like seconds, or hours, or years. He was like that for five whole _minutes?_ Just on his knees in the snow, gibbering like a lunatic, all because someone had turned his soul green?

"I. Uh. Jeez." Sans scrubbed at his cheekbones. He had no idea how to explain this. "I'm really sorry. That must have been super weird. I, heh, I guess I just really hate the color green, huh? Maybe that's why I've never liked salads. That explains everything, heh. All that healthy stuff is green."

"Sans, this was serious," Undyne said, holding her arms. "You were completely freaking out. It was almost like…"

She trailed off and looked away, frown deepening. She seemed to be thinking about something.

"Yeah, I'm sorry. That's pretty embarrassing. Listen, uh, it won't happen again."

"No, it won't," Undyne said abruptly. "Clearly I've got to train harder, so I never let something like this happen again. Not to anyone."

She gritted her teeth and clenched both fists at her sides.

"The Captain of the Royal Guard is supposed to protect monsterkind. I need to be better than this."

"Wait, but this was _my_ fault."

Papyrus rested a hand on top of Sans's skull.

"This absolutely, positively was NOT your fault, Sans."

"He's right. Every monster has their own pattern of bullets, their own ways of using magic. But I tried to push you into something that didn't come naturally to you. And of course defending wouldn't come naturally to you! I should have known better."

Sans felt like the scum of the earth. She was blaming herself, when _clearly_ this was his own fault, his own complete inability to function. How could she possibly have known that he would turn into a pathetic, trembling _mess_ when she used green magic? Hell, even Sans hadn't known. He hadn't even known that Undyne could use green magic at all. Turning bullets green was simple enough, and basic healing magic was almost universal, but full green magic…the last that Sans had heard, no one had been able to master it. No one but Gaster.

"Anyway." Undyne cleared her throat and set her empty tea mug down on an endtable. "If you're sure you're okay, then I think I'm gonna leave. Papyrus we can cancel our training session if you want."

"Oh, come on," Sans said, waving his hand as if the whole thing was absurd. "You don't need to cancel because of something this silly."

Papyrus tapped his phalanges together, making tiny clicking sounds.

"UNDYNE! I'm afraid we must postpone our super secret training session! But just for a few hours! I will be there for training at noon! ON THE DOT! NYEH HEH HEH!"

Undyne snorted a little.

"Alright, fine. I'll see you then." She headed for the door. "And Sans? Again-I'm really sorry. I hope you can forgive me."

She was gone before Sans could answer. Sans listened to her footsteps disappear down the front steps.

He slumped in the couch and sighed. So much for damage control. This entire day had gone straight to hell in record time.

"Bro, I'm…sorry. I must have really scared you."

"I thought you had Fallen Down again."

Sans went rigid, his eyesockets widening. He turned and stared up at his brother. Papyrus had his fingers laced together and was leaning forward on the couch, staring into space. There was that look again. Like he was on the verge of tears.

"Bro…"

"You collapsed. You were limp and unresponsive. It was...it was just like before. I thought you were Fallen Down."

"I…" Sans gripped the mug so tight his bones squeaked against the ceramic. "Bro, I'm sorry. I didn't…"

"Stop." Papyrus's voice wavered. _"Please_ stop apologizing."

Sans fell silent, staring into the empty mug. It felt like staring into an abyss. He felt like he was falling again.

"...Is that why you made me ketchup water?"

Papyrus just nodded.

"Papyrus, that…that hasn't happened in ages. Years and years. I got over it. I'm better now."

"I know."

"And it's not going to happen anytime soon. I've got…heh. I've got plenty of years left in me. I can't, uh, I can't leave until I've annoyed you with every last pun there is, right?"

Papyrus made a nondescript sound.

"Papyrus." Sans tucked his legs under him and turned on the couch so he was facing his brother. "Look at me."

Papyrus looked over at him. There was some wetness around the rim of his eyesockets. Sans felt like crawling into a hole.

Made him cry again.

Papyrus was still gripping his hands, so tight it had to be hurting. Sans reached forward and very carefully undid his fingers. Papyrus let him.

"I didn't Fall Down." He folded his hands into his brothers'. "I'm not going to Fall Down. It was just a stupid accident. Some kind of weird magical reaction. I'm okay. I'm not going anywhere."

Papyrus sniffled a little and held onto Sans's hands.

"I know, brother."

Sans smiled up at him. "Good. Cause, yanno. I can't have you babying me, yanno? That's supposed to be the big brother's job. What would the neighbors say?"

Papyrus chuckled a little.

"As if you care what the neighbors think. If you cared, you wouldn't go around in the same hoodie and slippers all the time!"

"Yeah, that's true. Everyone already knows I'm huge slob. So I've got a reputation to uphold. Don't wanna disappoint them all, right?"

"Nyeh! It's a terrible reputation! If you just put in a little more effort, everyone would be SO IMPRESSED!"

"Naaahhh," Sans said, milking the word for all it was worth. "Effort's no fun. I have to eff _use_ a sense of laziness to keep being legitimate. If I act eff _ete_ or eff _ervescent_ then people will think I'm a fake. That's not a very eff _icient_ way to make friends."

"OH MY GOD, SANS!" Papyrus let go so that he could dramatically throw his hands in the air. "STOP!"

Sans laughed despite himself. "You're smiling, though."

"I AM AND I HATE IT!"

Sans beamed at him. "So we good, bro? No more fussing?"

"I SUPPOSE," Papyrus said, folding his arms. "BUT! I am still going to keep you company until my training! I told Undyne I would be there ON THE DOT! And ON THE DOT I SHALL BE! So! We will utilize this time for BROTHERLY BONDING!"

"Sounds great," Sans said, stifling a yawn-for real this time. He leaned against Papyrus's side. "I could go for some of that."

"Nyeh," Papyrus said, quite emphatically. He draped an arm over Sans's shoulders.

Sans abruptly realized that he was exhausted. Ironic, seeing as he'd only woken up about an hour ago. He supposed it made sense. Going to pieces apparently took a lot out of you.

"Sans?"

"Yeah?"

"Why… _did_ you freeze up like that?"

Sans leaned more heavily against him.

"I've never seen you freeze up like that," Papyrus continued. "And whenever we spar together, you…you always look so uncomfortable when I turn your soul blue. You try to hide it, but I see it."

Damn. And here Sans thought he'd been doing a pretty good job.

He let his eyesockets slide closed.

"I'm sorry, bro."

"I told you to stop apologizing."

"Yeah. Sor-heh."

"Sans…please just tell me."

"I…"

Sans trailed off and was quiet for a moment, mulling things over.

"I just…don't like it when people mess with my soul without permission. But it's…it's okay with you, because you-you ask, and-and I trust you. I always trust you. It's not Undyne's fault, I mean. We were fighting, and she was actually-she was being more careful than I expected her to be. She seems reckless, but she's…really precise."

"Undyne is indeed pretty amazing," Papyrus said, idly rubbing Sans's shoulder.

"I just don't trust her like I trust you. And, uh, I've never been turned green like that before, and it was just-surprising? I couldn't…move, and…it made me feel…"

Weak. Powerless. Vulnerable. Pinned down like an insect to a board. Like a test mouse in a cage waiting for more pain. Like anyone could do anything they wanted to him.

Like a science project.

Sans realized he was clutching Papyrus's shirt again and let go.

"I just don't like it. That's all."

Papyrus was quiet for awhile, holding Sans a little closer, still gently rubbing Sans's shoulder. It was soothing. Sans couldn't help but relax.

He was safe. He had his brother.

"I could stop turning your soul blue when we spar."

"Don't you dare." Sans yawned openly. "I'm not letting you mess up your own magic just because of me."

"But, brother…"

"I'm not letting you. I'm pulling the big brother card."

He heard Papyrus sigh.

"Alright, then."

"Thanks. For…heh. For everything, I guess."

"I haven't done anything but be your amazing, incredible and very great brother." Papyrus tipped his head, resting it against the top of Sans's skull. "If you want to sleep, I will not protest. Even though you sleep far too much."

Sans smiled faintly.

He was asleep within minutes.


	10. For Nothing

.

 **ENTROPY**

* * *

Chapter 10: For Nothing  


 _Alphys, I didn't know you knew Sans.  
_

* * *

They were in a blank, black void, playing chess. Gaster really did have a flair for dramatic symbolism. He was even black while Sans was white. Horribly appropriate. Downright cliched.

Sans was not in the mood for this. Nor was he particularly any good at chess. He was better at cards. All the regulars at Grillby's said he had an incredible poker face.

He moved a pawn.

"You've been avoiding me."

This was the first Gaster dream in…he wasn't even sure how long. Weeks, maybe a month or more. For a little while, Sans was afraid that they'd stopped altogether, though he wasn't sure why the prospect scared him. The Gaster dreams were unsettling at best and literal torture at worst. But even so, even with everything that had happened and everything that Gaster had done to him…this was still the only way to reach him. This was still the only method Sans had to try and fix anything.

Anything at all.

Gaster wasn't even here, but a black pawn moved all the same.

"GUILT."

Sans gave an exasperated sigh and moved another of his pawns.

"More of this, huh? I mean, I guess the more of yourself you remember, the closer we get, but still. Guilt isn't exactly helpful."

"PITY."

Sans rolled his eyelights, glaring at the black chess pieces. It was better than glaring at nothing.

"Cool. Thanks. That's even bet-"

"NO…MISSPOKE. NOT THE RIGHT WORD."

Gaster moved another pawn, capturing the center of the board.

"SYMPATHY?"

"That's pretty damn close to pity, you know. But you always did love semantics."

Sans moved out one of his knights. It was somewhat bold, but he didn't care. He wasn't going to win, anyway. This wasn't the first time they'd played chess. They'd done it here, in this…dreamscape, or whatever you could call this place, during dreams when Gaster was calmer. They'd done it in real life, too, passing time while data compiled or new figures started rendering or while Betas machined this or that part. Sans hadn't won a single time. Gaster was an incredibly savvy player, and very ruthless.

"DETAILS. I LIKED…DETAILS."

"Yeah? Could have fooled me. You kind of skipped over the _small_ detail that you were trying to kill the entire Underground. And the detail that you'd made yourself Determined. And several other details I could think of. Make a move, Gaster."

"CHESS IS PATIENCE." Gaster moved another pawn. "YOU. ALSO PATIENT."

"Most of the time."

Sans captured the new pawn with his knight.

"I BELIEVE I. DID FEEL PITY. ONCE. AFTER YOU TOLD ME."

"Everyone does."

Gaster captured Sans's knight. Sans dug his fingers into the fabric of his shorts. The fabric that didn't even exist, because none of this existed. None of this was real.

He usually _was_ very patient.

"Everyone but Papyrus, anyway." He let go of his shorts. Tried to relax.

"BUT I KNEW. HOW COMPETENT YOU WERE. HOW CLEVER. PITY IS INCOMPATIBLE WITH…"

Sans moved out one of his bishops.

"With?"

"THE WORD, IT…" Gaster made a frustrated sound as he cast around for whatever word he was looking for. Sans tensed infinitesimally. Gaster hadn't hurt Sans in months now, and he hadn't even gotten particularly _angry_ in awhile, either. But it wasn't wise to let his guard down. Gaster could still lash out at any second.

"IT BEGINS WITH…" He made a sound that wasn't a sound. A sun symbol. Then he moved a knight.

"An R."

"I AM NOT…GOING TO HURT YOU, SANS."

Sans was so much better at poker.

"Sure."

"I AM MORE CONTROLLED THESE DAYS. DAYS? TIME IS AN ODD THING IN HERE. PERHAPS IT IS YEARS. THE IDIOM ESCAPES ME."

"No, it's days."

Sans moved a pawn. Gaster immediately captured it.

"CHECK. THIS. THE REASON I HAVE. AS YOU SAY. BEEN AVOIDING YOU."

"What, suddenly you don't want to hurt me?" He almost laughed. "That'd be a first."

"NEVER…WANTED TO."

"You can't kid a kidder, Doc."

"…RARELY. WANTED TO."

Sans moved another pawn to protect his king, still glaring at the board. Gaster would win in three more turns.

He didn't care.

"Whatever. Guess I appreciate you holding back."

Gaster carefully moved a bishop.

"YOU. MISUNDERSTAND. I HAVE NOT-IT IS…DIFFICULT. IN SOME WAYS, I SEE EVERYTHING. IN SOME WAYS, I SEE. NOTHING. DIFFICULT TO. COMPREHEND, ALL THE WAYS THAT I HAVE HURT YOU."

Sans pretended to study the board, looking for any possible way that he could win. He couldn't, of course.

"You're talking about what happened with Undyne."

"HAPPENED. IS HAPPENING. WILL HAPPEN."

Sans moved a knight in a cursory attempt to stop the inevitable. "Happened."

"YES."

"How...much can you actually see? Of the real world, I mean."

"AS I SAID. EVERYTHING. NOTHING. PAY ATTENTION. IT DEPENDS UPON YOUR. DEFINITION OF REAL."

Sans sighed. A complete nonanswer, like usual. Perhaps the resentment was hypocritical, given that Sans himself was a master of nonanswers. He wasn't really in the mood for self-analysis right now.

Gaster captured his knight.

"CHECK."

"It wasn't a big deal. It just reminded me, that was all. What's the point in worrying about it? It's never gonna happen again. Undyne will be too afraid to fight me. Too afraid she'll dust me or that I'll…lose my goddamn mind. Heh. It's been fun lately. The dumpy skeleton with 1 HP, turns out he's not just weak and useless, he's also _crazy."_

He moved his king, trapping it.

"YOU ARE NOT INSANE, SANS."

There was a pause. Sans stared at the piece that he knew was about to move.

"IT WAS MY FAULT, ANYWAY."

Gaster moved a bishop.

"CHECKMATE."

Sans reached over and tipped his king onto its side.

"Never could win against you."

"INACCURATE."

"Heh. Not at chess, at least. You know, sometimes I wish…" Sans spread his hands over the board helplessly. "I wish I could just hate you. It'd be so much easier."

"I HAVE REMEMBERED THE WORD."

"Yeah?"

"RESPECT."

Sans looked up, but there was nothing to look at. Just blank darkness. It wasn't even really darkness. It was just…void.

"...Respect."

"YOU ARE ANGRY."

"Yeah. Yeah, no kidding. _Respect?_ I'd ask if you were joking, but, uh. You don't joke. _Respect?"_

It was odd. Gaster said he was angry. Sans acknowledged that he was angry. And he _was_ angry, but the feeling of it was…strange. Like he couldn't quite muster the energy to be actually angry. It felt far off, muted.

Sans swept a hand across the chessboard, sending several pieces flying. They hit the floor of the void soundlessly and rolled away into nothing.

It still felt far away. Unreal.

"From day one." He paused for just a split second, because here it was again, here he was about to go off on Gaster again, and it just made him _tired._ "From day _fucking one."_

Angry people swore and put emphasis on their words.

"From day one, all you saw was what everyone else sees. You said so yourself. You hired me because I was just barely smart enough to be noticeable. I was just _barely_ interesting enough. And then you found out about my HP."

He was staring at the chessboard. His voice had lost any real anger, any real venom or volume.

"Hindsight is twenty-twenty. I tricked myself into thinking you were different. That you actually valued me at all. That you…respected me, as you said. But I noticed how things changed after that, Doc. Suddenly, everything was about fixing me. About seeing me better myself. Giving me magic. Pushing me to learn blue magic. Pushing me to go after humans."

Sans picked up a black pawn and rolled it across his hand, listening to the stone click against his bones.

"Everything you said to me in the bottom of the Core was true. You saw what everyone else saw. I had no value whatsoever beyond what you could shape me into. I was a science project."

"SANS."

"A puzzle to be solved. Something broken to be fixed. You were the same as everyone else." Sans closed his hand around the pawn. "Every doctor who thought they could cure me. Every teacher who wouldn't let me touch a Bunsen burner. Every neighbor or stranger who told me I should just train more, or eat healthier, or go for a jog every morning, or stare at a pretty flower."

He let the pawn fall out of his hand and felt himself grin.

"There's nothing respectable about me." He folded his hands in his lap. "Nothing at all."

There was a long silence, long enough that Sans was starting to think that Gaster had simply left. Had finally gotten bored with his science project and opted to leave it alone. Maybe let it grow some interesting mold. Heh. Sans wondered if he could sit still for long enough that mold would actually grow on him. Maybe he would try it out.

"I DO RESPECT YOU. SANS."

"Sure."

"YOU ARE SEEKING SOMETHING. FROM ME. SOMETHING I CANNOT GIVE. YOU KNOW THIS."

"Yeah." The word dragged out of him, less a word than a sound of exhaustion, resignation. "I do know."

"ANGER. LIKE GUILT. IS NOT PRODUCTIVE."

"Yeah. But I was never too good at being productive."

"NOR IS. SELF-PITY."

"Ah. Is _that_ what you think that was."

Gaster didn't answer.

"I'm not angry anymore." Sans chuckled. "I don't really care at all. I think, uh. I think I'd like to wake up now."

"WAIT. WAS NOT FINISHED. THERE IS. SOMETHING YOU MUST KNOW…"

"Tell me later."

Sans woke up, before Gaster could say another word. His eyesockets opened and he stared up at his bedroom ceiling.

Usually he was stressed or frightened or outright panicking after a Gaster dream, even the most benign of them. Right now he felt strangely empty. Not really in a hollowed-out sort of way. It felt like nothing.

Nothing at all.

* * *

Dogaressa's father, Doggerel, had finally decided to retire from his Snowdin sentry post. No one ever thought he would actually do it. The dog was _ancient,_ and had been at his post for as long as anyone in town could remember. Everyone had assumed that he would just keep working until he Fell Down, or skipped over that part entirely and went straight to dust. Dogaressa had been trying to talk him into retiring for years to no avail.

Doggerel worked one of the primary sentry stations. It was deep in the woods, far from town and a few caves over from Papyrus's station, and was thought to be the closest station to the Ruins. Of course, no one had been able to actually _find_ the Ruins for several decades now, but everyone knew that's where the humans were coming from. Any human who came through the Underground would have to pass by Doggerel's station.

Which might have explained how five humans had made it so deep into the Underground. Doggerel had been an incredible Guard Dog once, and then an incredible sentry, but that had also been decades ago.

In any case, the station was a priority location, and could not be left unmanned.

"So how did _my_ name come up, then?"

It was breakfast in the skeleton household, and Papyrus had been regaling Sans with news as they both finished their coffee. Papyrus beamed at his brother.

"Because you are an EXCELLENT sentry, even if you fall asleep at your stations and slack off ALL THE TIME! And because you're the only one who, despite that, can SOMEHOW maintain multiple stations? And also because…apparently recruitment is down and therefore your name is at the top of a short list!"

Sans grinned slowly. "Yeah? How short a list we talkin' here?"

"A…SHORT ONE!"

Sans chuckled a bit. He had known that recruitment for both sentries and Royal Guards had been down for the past year or so, but for _Sans_ to be considered for a priority position could only mean one thing.

"Let me guess. So short it only had one name on it?"

"MAYBE! BUT THAT IS BESIDE THE POINT! The point is, you are a GOOD sentry, and your talents have been recognized! YOU'RE MOVING UP IN THE WORLD, SANS! And we will finally be working right next to each other! Practically a stone's throw away! That is, if you decide to accept the job?"

Sans polished off his coffee. Another sentry station. That would bring the grand total up to four, which was completely absurd. Not that sentry work was difficult in the slightest. Four times the pay, four times the breaks.

And he'd be closer to his brother.

"Yeah, sure, I guess I can take it if no one else will. Such a high-profile station? It would be silly _four_ me to say no."

"EXCELLENT! I was hoping you would say-wait, _ugh,_ that was a pun, wasn't it? YOU ALMOST GOT ME ON THAT ONE, SANS! BUT THE GREAT PAPYRUS! IS FAR TOO VIGILANT!"

"Pfft, yeah. Nothing gets past you." Sans rose from the table to set his dishes in the sink. "I'll let the dogs know later today."

"I'm so PROUD of you, Sans!" Papyrus said, standing as well. "To think! Only a few years ago, you had ZERO jobs! Now you have-LIKE FIVE!"

"Yeah. Heh. To think. Also, I think it's six, if you count the hotdogs."

Papyrus made a grumbling sound. "AND AS BOTH YOUR LOVING BROTHER AND A SENTRY AND A FUTURE ROYAL GUARD! I must remind you! That selling hotdogs from your sentry station is TECHNICALLY ILLEGAL!"

Sans gave a languid shrug, sauntering out of the kitchen to go gather his things.

"Only illegal if I get caught, or if anyone cares."

"NYEH! THAT IS NOT THE DEFINITION OF ILLEGAL! ALSO, Sans, can't you AT LEAST remember to AT LEAST rinse out your coffee mug?"

After a little more bickering, the two of them parted ways and headed to work. Today was a shift at Sans's Waterfall station, which was good. He needed to replenish his supply of water sausages. Hotdog sales had really taken off, to the point where people had started to complain that Sans wasn't at the Hotland station often enough. He had thought about selling them out of his other stations as well, but that seemed like too much work. Plus if he started selling them in Waterfall, people might make the connection and finally realize they were paying 30 G for basically a weed. That would be no fun.

It was a quiet day in Waterfall, which was also good. Sans's nerves, so to speak, had been…somewhat on the fritz lately. Or maybe not "lately." He was supposed to be a chill guy, the most easy-going monster in the Underground. But for almost two months now, it was like the smallest things got to him. He was jumpier than usual, flinching at the slightest sounds. He hadn't been sleeping well and was having nightmares again-plain old ordinary nightmares that often had nothing to do with Gaster. The lack of sleep meant he was napping more at his stations and left him irritable. Fortunately, he had always been good at keeping irritability and annoyance to himself. Mostly.

He had also been spending more evenings at Grillby's. Papyrus was starting to notice.

It didn't take a genius to know _why_ this was happening. But, whatever. Sans didn't have the time or energy to try and address it. Last night had been mostly fine, the last Gaster dream had been several days ago, and either way, he had more important stuff to focus on. Like collecting water sausages, and figuring out how to work a fourth sentry station into his _extremely_ busy schedule. A schedule that was at least 80% naps, breaks and generalized slacking off.

No one worked as hard at slacking off as Sans did, Papyrus kept saying. But at least it was a way to keep himself busy. Or at the _very_ least, distracted.

Sans filled three cardboard boxes with water sausages over the course of his shift. He was pretty sure that he was, in some way, doing a kind of public service. Water sausages grew _everywhere_ in the marshes, to the point that they were choking out some of the echo flowers. No one else wanted water sausages for anything but decoration, so no one else was really bothering to tear them out. The "sausage" part made up such a small portion of the plant, though, and he never had any idea of what to do with the rest of it. He would usually just toss the stuff further into the marsh. On days when he was more bored he'd take the plants to a waterfall and watch them go over the edge. It was stupid and amusing. Today was a fairly boring day.

He needed to swing by the dump anyway, see if any intact condiments had made it down the rivers. It was cheaper than buying ketchup and such from the store.

Sans teleported himself and an armful of plant detritus to the dump, landing on top of one of the bigger piles. He clambered down the side and made his way toward the waterfall, keeping an eyesocket out for condiments or anything interesting. Sometimes human books made it down here intact, usually when they were wrapped in plastic. Sans remembered coming here once as a kid and finding a human book titled _The Hitchhiker's Guide to the Galaxy._ It was the first time he'd realized that science, even science fiction, could actually be funny.

In fact, he'd found most of his favorite Surface books in the dump. Fun stuff like the Mars Trilogy. Interesting stuff like _The Elegant Universe._ Retroactively ironic stuff like _A Brief History of Time._

Stephen Hawking eat your heart out.

He'd been keeping an eyesocket out for the back half of _Restaurant at the End of the Universe_ for a decade now with no luck. Not that it mattered all that much. Sans had sold the first half, as well as all the others he had, a few years back to pay the rent. He had considered trying to start a collection again, but Surface books were rare.

Not much point.

His mind was wandering, which was fine by him. If it was wandering it meant he wasn't thinking about other things. Like the still-broken machine, and the still-broken timeline and the still-broken Gaster. And the possibly-broken Sans.

There were no books in any of the trash piles on the way to the waterfall, nor were there any condiments that hadn't expired. Sans reached the waterfall, the biggest in the Underground, the one with the slow current and the drop that led hundreds and hundreds of feet down into black nothingness. He climbed onto a pile of waterlogged wood that served as a sort of platform and started tossing plants into the water. The current tugged them along at a lazy pace until they neared the edge. Then they suddenly rushed forward, as if eager to meet the darkness below. Then they were gone.

It was weirdly relaxing.

Sans had been at it for about five minutes when he heard splashing footsteps, followed by a voice.

"Sans?"

He looked up. Alphys had emerged from behind a tall pile of garbage and stopped, peering at him with a mix of surprise and confusion on her face.

"Oh." He blinked at her, then grinned. "Hey, Al. Been awhile."

He hadn't seen her or even spoken to her since she had swung by his hotdog stand the one time.

She tilted her head. "What are you doing out here?"

"Uh." He looked down at the pile of plant material beside him. "Nothing? Throwing plants into the water and watching them go over the edge, I guess."

"Oh." She nodded slightly as if this was a perfectly normal activity.

"Sorry, it's a _really_ boring day. Waterfall's quiet."

"C-Can I throw some plants with you?"

She sounded completely exhausted.

"Sure. I've got plenty left." He held out a few bits of green as she approached, her tail dragging in the water. The edges of her labcoat were already soaked. "What are _you_ doing out here, anyway?"

"I come out here all the time," Alphys said, taking the plants. She stepped up onto a bit of rock nearby, tore off a strip of leaf and tossed it in the water. It drifted along before disappearing over the edge.

That didn't answer the question, really, but Sans decided not to press.

"So how're things going at the lab?"

She tore off another bit of leaf and dropped it in the water.

"It's fine. Uh, things are kind of starting to come together, a little? I've been testing this, um, n-new invention, and it's working pretty well and…it's given me a bunch more ideas for some stuff."

He chuckled a bit and snapped off a bit of stem to toss in the water.

"Heh, but you can't tell me what it is or what it does, right?"

"Nope. Classified."

"Well, I'm glad to hear it's going well."

"Yeah. Um, thanks."

There was a silence, broken only by the rush of water and the sound of tearing plant material.

"So, uh…" Sans put in after awhile. "I have a bit of good news too, sorta? I kind of had a bit of a breakthrough with the machine. I mean…sorta. I've got a way to repurpose some bits of it into a sort of…meter. It'll basically extrapolate the data it generated on its maiden voyage to calculate where the biggest holes in the timeline are. I just need to put it together. I think I can also get it to sort of track changes as well, identify if spacetime is tearing or stabilizing. See if anything new happens to the timeline. Just need to put the system together."

Alphys glanced over at him as she threw a plant stem.

"That's…good news. I guess it'd be good to, um…see w-where the worst of it is. Or if any humans have done any Saving, I guess."

Sans tied one of the longer leaves into a ring and gave it a bit of a spin when he tossed it. The leaf ring spiraled away over the edge.

"Yeah, that's what I was thinking. Kind of borrowed from some of the stuff your dad and Gaster left behind. But, uh…I could really use an engineer's input. I mean, no pressure. No rush or anything."

Alphys's shoulders had gone tense and she was tying her current leaf into knots.

"Just, uh, yanno. When you have free time, I guess?"

She snorted a little. "Heh, free time. What's that?"

"Heh. Fair enough. Just, uh. You know, whenever."

"Well…spacetime hasn't come unravelled yet, right?" She chucked the leaf knot. It bobbed for a moment, then sank. "I-I mean, I think if it was going to, it would have done it by now. It's been, wh-what…how many years now?"

She frowned and abruptly looked over at him, confusion on her face.

"How many years?"

"I…four, I think. I'm not…" Sans rubbed at his skull. "I'm not sure. It kinda blurs together."

"Yeah, I know what you mean," she said, and there was that exhaustion again. "I thought it was five years."

"Heh."

"Sans, do you really…" Alphys paused and sighed. She threw her last leaf, then folded her arms. "Do you really think we can fix the machine? Even if we work on it f-for another four years? The technology is still all wrong. We're still nowhere near the level you guys were at when the m-machine was built. The Underground just hasn't incorporated soul power the way you guys had, and I'm sure as heck not…I mean, I hoped when I got to work with the souls that I might be able to crack it, all of it. The machine, my dad's device thingy. Figure it a-all out, you know? But I'm…"

She gripped her elbows tightly.

"I'm only just now figuring out how human souls even work. And I'm so focused o-on the…the stuff I'm working on that I haven't been able to even think about using soul power. For, for anything. And I know I haven't been able to help you with the machine i-in like a year or more now. I mean, not in any really helpful capacity, and I feel…I feel really bad about that. But at the same time…"

Sans wasn't looking at her. He was staring out at the edge of the waterfall, watching his leaf bits go over the side. This place made a monster feel…contemplative. There were so many stories about this waterfall and about the other really big ones in the region. All the ones that plunged away into endless darkness. No one really knew where they went. Monsters made up stories to tell their kids about massive lakes full of dangerous creatures. Or they came up with theories, some far-fetched, some less so. Like, the water probably poured all the way through the planet, right out onto the Surface on the other side. Or there was nothing at all down there, and the water simply disappeared, eaten up by strange magic.

"At the same time?" he prompted after a minute.

She shuffled her feet, labcoat meeting the water again with a soft, dragging sound, like a snake through a pond.

"I just…don't you think it's…" She sighed heavily and Sans turned to her finally. She gave him a nervous look.

"D-Don't you think it's time we gave up? You know…moved on?"

Sans was grinning, but technically he was always grinning.

"'We'? Cause I'm pretty sure _you_ gave up months ago."

She frowned. "D-Don't be like that. You know I just-haven't had time. It's not easy, being the Royal Scientist."

He almost laughed. _God,_ he almost just lost it right then and there, but his grin just widened. It wasn't easy being the Royal Scientist. No, of course it wasn't _easy._ Royal Scientists had so much to think about, so many responsibilities. They had an entire Underground to look after. They had to prioritize, that was obvious. You couldn't think of everything as equally important, not when you were in a position like that. You'd drive yourself crazy, never able to make a single decision.

You'd drive yourself _crazy._

"I can't just give up, Al." He shook his head. "The timeline needs to be fixed."

"But what if it _can't_ be fixed, Sans? Have you thought about that? Wh-What if we're just…what if this is just one of those things you can't fight? I've…I've been holding onto this false hope that I'll…that I'll get my dad back someday, and it's…it's been _messing me up._ It messes with my head. I think it's messing with you, too. I keep hoping, but I…"

Her head lowered, her gaze dropping to the water's surface, her shoulders sagging.

"He's gone. He's dead. Him, the old Royal Scientist. Th-They're…they're dead, and I just need to…I need to accept that, and…and just move on. I-I'm sorry, Sans, but I just can't…I can't keep going like this, hoping that one day w-we'll just miraculously fix everything and I'll g-get him back. I can't k-keep living on a false hope."

This was strange. Sans felt like he should be angry. And he _was,_ nominally, but at the same time everything felt far away. He pulled his arm back and threw the last water sausage stem overhand, arcing it into the water. It got stuck in the detritus underneath and ended up sticking out over the edge, as if pointing.

"Well. I've told you a thousand times, if you don't want to work on it anymore, you don't have to. I'll figure it out on my own."

He always had, but he didn't add that part. He was trying not to sound bitter. Trying to be understanding.

"I'm worried about you," she said again. "I mean, judging f-from how all of this has been making me feel the past few years…you must feel even worse. A-And I think it's affected you. Maybe…maybe you should just let it go?

He stared at her with empty eyesockets.

"Al, do you have any idea what happens to guys like me when we _just let go?"_

She gave him an appalled look, face going pinkish with embarrassment.

"I d-didn't mean it like that. J-Jeez, Sans, y-you know I didn't mean it like that!"

"No, I…" He looked away and blinked, forcing his eyelights to come back. "I mean, of course you wouldn't know, heh. There are no guys like me. Not like I talk about it, either. Look, I'm…sorry. I get it, I do, but-Al, I _can't_ give up. I have to try and fix it, I mean, I have to at least _try."_

"You've been _trying_ for four _years."_

"But your dad isn't-he _isn't_ dead." Sans gritted his teeth for a moment. He couldn't tell her, absolutely couldn't tell her about the gray monster at the pier, separated from true reality by a few degrees. "He-we can still save him. Him, Gaster, everyone else who fell."

"Sans." Her voice broke. "I can't even remember his _name."_

His eyesockets widened at her.

"What?"

She clutched at her headspines and made a strangled little noise. "I can't even remember his _name!_ I've been trying to _months_ to remember, Sans! It was just-it was _gone_ one day, and I couldn't get it b-back."

"It's…" Sans trailed off, frowning, gaze shifting to the middle distance. "His name was-it-it began with a B."

He pressed a hand to the side of his skull. It was there, it _had_ to be there. He had drawn that ridiculous picture, had written the words _don't forget._ He couldn't forget. He couldn't. Memory was all he had.

"B…B something, it…"

"He's _gone,_ Sans." Alphys drew a shaky breath, releasing her head. She looked up at him. Her mouth was trembling as she forced herself not to cry. "He's just _gone._ He's _dead."_

"No, I've got it. I just need a second."

B. It started with B. He'd been taller than Alphys, with green scales. He wore glasses like she did, stuttered like she did. He'd been brilliant. A wonderful guy. Warm, friendly. Loved his work, loved his daughter.

B…

It was gone.

The stem in the water unhooked itself and went tumbling away into darkness.

Four years. Four years, and there was nothing. Nothing at all to show for it. A broken machine, a grayed out monster who would never move from that spot on the pier. A nonexistent monster who was just barely starting to achieve any coherency.

And a skeleton, who was losing pieces of himself every single day.

"But I can fix it." Sans's voice sounded hollow, even to him. "I can…"

He turned a judgmental glare on Alphys.

"How can you just give up on him?"

Her eyes widened. For a moment, she looked thunderstruck. She wilted, almost folding in on herself, her arms shifting to hug her middle instead. Then, in an instant, her eyes turned flinty. She drew herself up. A hardness came over her, the same hardness Sans had seen from her father, very rarely.

He'd…he'd screwed up.

"Wait…Al, I…"

"You think I _wanted_ this?"

She wasn't shouting, not quite. She was like him-had probably shouted maybe twice in her whole life. It just didn't come naturally to her. But this was still the loudest he had ever heard her.

"You think I wanted _any_ of this? You think I wanted to f-f-forget my own father's name? Y-You think I w-wanted to forget losing him? Cause-cause that's what it is, Sans! I _lost_ him, and-and even moreso than people _usually_ mean when they say they lost someone! My own dad! I-I'm the only one who even remembers him! My aunts and uncles, e-everyone else, th-they all forgot him! I-I have what he looked like, I have what he was _like,_ little things, like, l-like stories he would read me as a kid, o-or the teddy bear he got me one time, o-or how he c-couldn't cook anything but grilled cheese, i-it was always grilled cheese."

Alphys took a step closer to him, fists balling at her sides. Sans took an instinctive step back, toward the edge of the waterfall.

"Al, I'm-"

"That's all I have. My _dad,_ and that's all I h-have left of him. He's _gone._ He's dead, he's _gone,_ and he's gone _because of you!_ Because _you_ had to drag him b-back into the whole mess!"

Ice flooded Sans's bones, down to the marrow. He went still, eyesockets wide, eyelights going out.

There was a ringing silence.

All at once, the fight ran out of Alphys. She took a step back and covered her mouth with a hand. Her eyes flicked back and forth before settling on Sans again.

"Oh god, Sans, I'm-I-I didn't mean that."

"Oh."

There was no emotion in his voice at all.

"Sans, I-I didn't…I was just angry, I didn't mean it. Please, you _know_ I didn't…"

It occurred to Sans, for some reason, that he was only four, maybe five steps away from the edge. Four or five steps. That he could just…keep stepping backward, four or five times, and then…

Odd thing to think about now.

"No," he said, because he had to say something. He stuffed his hands in his pockets. "You're right."

"Sans, no, I-"

"I called for help." It felt like he was back there. Hiding his phone against his chest as Gaster contemplated whatever he was contemplating. Typing out a frantic message. Signing the monster's death warrant. Not just him, either. Scientists, guards, everyone who had come running. How many of them? Sans hadn't even counted. Their names were gone as well.

"I called for help, and he came. He was out. He was out of it. He was safe. Until I called for help. He was a good guy."

He'd been a good guy. A real stand up monster. His friend had called for help, and he had come. Even though he must have known what might be happening. Even though he knew he might not come back.

He was gone. All of them were gone. And it was Sans's fault. It wasn't just self-flagellation, wasn't just Alphys saying something in anger. It was demonstrable. It was fact. If not for Sans, Alphys's father and the rest of them would still be alive.

If Sans had acted sooner instead of ignoring the warning signs, _Gaster_ would still be alive.

Why? Why was _he_ alive, when the rest of them were _gone?_ Why was a good person, a good father gone, why were _all_ those _good_ monsters gone, when _Sans_ was still here?

It occurred to Sans, for some reason, that falling down might feel very much the same as Falling Down.

He took a step off the platform, away from the edge and away from Alphys. The cold water soaked into his shoes again.

"Sans, wait. Wait, please."

Her voice shook. He thought she might be crying.

"I'm sorry," he said. "I'm…"

What else could he say?

He shook his head and started walking.

"I'm sorry."

"Sans, wait!" She called after him, but didn't follow. He kept walking. "I didn't mean it! C-Come back!"

As soon as he was hidden by a pile of trash, he teleported, away from Alphys and the waterfall. He didn't go back to his station. He went home. It was still hours before his shift ended, but he didn't care.

He lay down on his unmade bed and stared up at the ceiling.

* * *

Sans woke hours later to someone banging on his door. He started to sit up, then groaned and rolled over instead.

"Mmmff. 'M sleepin', Paps."

"SANS! ARE YOU AWAKE?"

"Mmnope."

He wasn't speaking loud enough for Papyrus to even hear him, but he didn't feel like raising his voice.

"BROTHER, I'M COMING IN!"

Sans sighed into his arm. Papyrus opened his door and Sans kept his eyesockets closed, lying very still. He heard Papyrus cross the room.

"Ugh, it's FILTHY in here! Sans! SANS!"

He had to be standing over Sans's bed. Sans could imagine him, hands on his hips, probably tapping his foot, glaring down at his lazy older brother.

"Brother, I KNOW you are only pretending to be asleep!"

"Mmm. Nah. 'M fast asleep." Sans snored a little as if to prove it.

"Very funny! Have you been here this WHOLE time? One of the ROYAL GUARDS called me earlier! I was of course VERY EXCITED to talk to a ROYAL GUARD! Until he told me that he was LOOKING for you, because you had ABANDONED your post! Sans, is that true?"

Sans yawned. "Can't talk. Sleepin'."

"SANS, BE SERIOUS! This is important! How could you just ABANDON your post? That's so irresponsible! And you've just been SLEEPING since then? You're SUCH a lazybones, but usually not THIS MUCH of one!"

Sans's grin widened. "That's me. Mr. Irresponsible. A disappointing lazybones."

Papyrus gave Sans's shoulder a push. Sans still didn't open his eyesockets.

"This isn't FUNNY, Sans! You cannot just ABANDON YOUR POST! And what about the dogs? They said they didn't see you either! I thought you were going to talk to them about Mr. Doggerel's station!"

"Yeah, uh…I will. Just forgot. I'll talk to 'em tomorrow. Just lemme sleep."

Sans started to roll over, but Papyrus caught his shoulder and didn't let him.

"At this rate, you've been sleeping for almost EIGHT HOURS already! It's almost midnight! Wake UP, you lazybones! We need to TALK about this!"

"Papyrus." Sans's voice quieted. "Please. Just let me sleep."

There was a silence. Papyrus let go of Sans's shoulder.

"Brother…are you feeling well?"

Sans felt the back of Papyrus's hand press to his forehead. Sans reached up and brushed it away.

"I'm fine, bro. Just tired." He let his arm drape over his eyesockets. "Just got tired at work and decided to come home, that's all."

"Are you SURE you're alright?"

"Am I fired yet?"

Papyrus sighed heavily. "I don't think so, but I would EXPECT you to get a reprimand at the very least!"

"Then I'm fine."

He went to roll over again. This time Papyrus let him.

"…You really just want to sleep?"

"Yeah. I'm just real tired."

"Do you want any dinner? I could make spaghetti! You could finally try some and tell me how it is!"

"Rain check, bro? I'm not hungry."

"You should eat SOMETHING, Sans!"

"Not hungry."

Papyrus fell silent. Sans tried to will himself back asleep. He really should just find it in him to get up, just get up like a normal person and eat some spaghetti. Should stop worrying his brother. But every time he thought about it he remembered that his shoes were still wet from Waterfall, and that he had left his boxes of water sausages at his station. That he'd have to go back there eventually and get them. That he'd have to go to work tomorrow in Hotland, at the station only a stone's throw from Alphys's lab. That he'd just left her there. Hadn't even bothered to make sure she was alright. And she _wasn't_ alright.

Getting up felt like an impossible. Downright herculean.

"Tomorrow, bro. Okay?"

Tomorrow was another day. He was just…in a funk, that was all. He'd had a bad day. Everyone had bad days. He'd just sleep some more and then wake up, and it would be tomorrow. Tomorrow would be better.

There was a long pause. Finally, Papyrus sighed.

"Okay, Sans. Tomorrow."

Sans listened as his brother walked away. Listened to the door open and then close. Listened to his brother's fading footsteps, down the hall and then the stairs. Listened until he couldn't hear Papyrus anymore.

He curled up a little on the bed and buried his face in his pillow.

* * *

The dogs were understanding, as dogs always were. Sans went to see them as soon as his Hotland shift was over, and told them he'd be happy to take over Doggerel's post. Doggerel himself had showed him the location. Sans didn't think he'd ever seen so much dog hair in one place. Doggerel had spent most of the time telling random, somewhat nonsensical stories about his long years as a sentry. The old dog was melancholy at the idea of leaving his station, so Sans told a few dog jokes and assured him that he'd treat the station well.

Doggerel became tired and shaky before too long, so Dogamy walked him home. Dogaressa and Sans lingered at the station.

"(I appreciate you putting him at ease, Sans.)"

He grinned up at her and shrugged, idly pulling a box of stale dog biscuits out from behind the station.

"Heh, I'm an _easy-_ going guy. It's practically my job."

He held out the box to her and she took them, sniffing at the box. She narrowed her eyes slightly, apparently debating whether they were still edible or not. Finally, she seemed to mentally shrug and popped a biscuit into her mouth.

"You know, I don't think I've ever been out to this part of the woods. I usually don't go further out than Papyrus's station." Sans looked down a path that wound away into the forest, disappearing into the dark area where the trees were much bigger. "How much further does it go, anyway?"

"(Not sure! No one ever patrols out that way. No one lives out there. Not even the teenagers go that deep. Would you like a biscuit? I think they're fine for skeletons.)"

"Heh, nah. I'm okay. So you want me to start next week?"

She nodded. "(Paw wants to clear it out first. He's nostalgic. Dogamy is the same way.)" Her voice took on the dreamy tone she always got whenever she talked about her husband; the same tone Dogamy got when he talked about her. Sans stifled a laugh. The Dogi were always kind of adorable.

"Well, don't worry. I'll treat the old place right. Hey, you and the other dogs thinking of hitting Grillby's later? Give Doggerel a send-off?"

She beamed, delighted. "(That sounds like a lovely idea! Though, less rowdy than usual. Something quiet for Paw. )"

Sans grinned. A quiet, low-key party at Grillby's sounded perfect, though knowing the Guard Dogs it wasn't likely to stay quiet for very long. That was fine; Sans could use the distraction, and he thought Doggerel and Dogaressa could use one as well. No one was going to admit it, but Doggerel wasn't doing well. Sans hadn't known how bad he was until he'd seen him in person earlier. The poor old dog was palsied and could barely walk.

"Cool. I'll see you all later, then. Meantime, I'd better get going if I wanna be on time for my after-work nap."

Dogaressa snorted and chuckled. "(So lazy! You sleep like a cat.)"

Sans headed home. Papyrus was making spaghetti when Sans got there. Apparently, Papyrus had taken "tomorrow" literally. The smell coming from the kitchen was somewhat remarkable. It smelled a little like Papyrus was trying to boil batteries.

"So, uhhh," Sans said, waiting at the table for Papyrus to finish. "How are the cooking lessons going, anyway? How excited should I be?'

"You should always be A THOUSAND PERCENT EXCITED for spaghetti from the GREAT PAPYRUS, BROTHER!" Papyrus called from the kitchen. "And they are going VERY WELL! We have moved onto the NOODLE part of cooking spaghetti! It's a VERY DELICATE PROCESS, boiling noodles!"

"How come it kinda smells like you set the box on fire?"

"NYEH HEH HEH! THAT IS PART OF MY COOKING METHOD!"

The spaghetti ended up being al dente noodles, boiled with bits of cardboard, at least an entire cup of salt, and what smelled like an entire container of pepper. For seasoning, Papyrus had said. There was no sauce, since apparently Undyne hadn't gotten to that part yet. Sans stared at the plate in front of him, pushing a bit of cardboard around with his fork.

"It looks, uh. It looks real great, bro, especially for a first attempt."

"REALLY? Thank you, Sans!"

Papyrus was, notably, not eating his own spaghetti. He was watching Sans from across the table with rapt attention.

Sans poked the spaghetti with his fork. It made a crunching sound.

The things he did for his brother.

He grinned, twisted his fork in the spaghetti, and took a bite.

It was a bit like trying to eat a pile of salt. Salt with a side of gravel.

"It's…uh…"

Sans forced himself to swallow.

"It's…ghh…interesting, bro. Never, uh." Sans hiccuped. "Never tasted anything like that before."

Papyrus's grin broadened.

"WHAT STIRRING COMPLIMENTS! The Great Papyrus has a long way to go before I can call myself a TRUE SPAGHETTORRE, but it is CLEAR that I have a natural TALENT! As I do with most things!"

"Heh." Sans set his fork down and drank an entire glass of water to get the taste out. "You sure do, bro. Uh, I'd eat more, but I'd better save room for the shindig tonight. You going?"

Papyrus folded his arms and heaved a sigh. "Does it HAVE to be at Grillby's?"

"Yep?"

"FIIIIINE! It is for an honored elder and friend, so I will go! BUT! Don't expect me to stay for long! I can't abide that GREASE PIT!"

Sans just laughed.

They left for the party about an hour later. Papyrus insisted on dressing up a little, saying that Doggerel would appreciate the formality. Sans pointed out that dogs were the least fancy monsters in the Underground and just went in his usual hoodie and shorts. Grillby's was packed. Half the town was there, including all of the dogs. There were even several Royal Guards from out of town, old friends of Doggerel or simply people who respected him. Undyne came by as well.

It was the first time Sans had seen her since their mock battle, but that was fine. He wasn't technically avoiding her-he just made it so that he had no real reason to talk to her. He was pretty sure that she was the one during most of the avoiding. That was also fine. It was probably better that way.

The party went almost exactly as Sans had predicted. It started out relatively quiet, people congratulating Doggerel on his retirement, asking after his health and buying him celebratory drinks or items from the dog menu. Once people started getting food and booze in them, however, things started to get louder. Doggerel, for all that he was ancient, was still a dog, and was just as prone to bouts of wild energy as any of the others. Once he started challenging monsters to arm wrestling matches, things got as rowdy as they always did when the dogs had a night out at Grillby's.

It was around that time that Papyrus found Sans amid the chaos and told him that he was going to head home.

"DOGGEREL BEAT ME TWICE! WITH BOTH ARMS! PAWS?" Papyrus yelled, louder than normal to be heard over the noise. In the background, Doggo Sr. and Greater Dog had started wrestling on the floor.

"Heh, well the guy was a legend. Guess he still is."

"I AM GLAD THAT HE IS HAVING FUN AT HIS RETIREMENT PARTY! BUT! A ROYAL GUARD IN TRAINING MUST HAVE AT LEAST TEN MINUTES OF SLEEP PER NIGHT! ARE YOU COMING, SANS?"

"Nah, I'm gonna stay out a bit longer. You go on home, bro. Get some sleep."

Papyrus's expression became sour for just a moment, but he buried it under a smile.

"…I'll read you two bedtime stories tomorrow to make up for it, okay?"

"I WILL HOLD YOU TO THAT, BROTHER! SEE YOU LATER!" Papyrus squinted at Sans. "OR…PROBABLY TOMORROW!"

Sans chuckled and waved him off.

The party continued on in much the same fashion. Sans had never really been much for this level of noise and mayhem, but it was incredibly amusing to watch. He tended to hang back at the bar, away from the dogs' tables, calling out jokes and puns at every opportunity. It was nice seeing everyone having so much fun.

Eventually, Doggerel was visibly becoming worn out, even though he was still challenging everyone who came close. Dogaressa managed to calm him down and convince him to call it a night. Doggerel said his goodbyes and everyone gave him another round of congratulations. Then Dogaressa and Dogamy escorted him home. Things started to quiet down after that. Sans lingered at the bar, chatting with the regulars and Grillby himself. Grillby was a monster of very few words, if any, preferring to communicate with crackles of flame and penetrating, eyeless stares. One of the regulars, Redbird, had ages ago taken this as their cue to be Grillby's semi-official translator, though half the time Sans was pretty sure that they were just making stuff up. Sans preferred to talk to Grillby without a filter. Grillby seemed to like his puns, and was overall a good listener when you were rambling on about sentry work or your cool brother after a few too many drinks.

The night was waning and several more guards and dogs had left when Sans found himself alone at the bar, nursing a bottle of ketchup and a drink. He wasn't sure what number this was, but he was definitely a bit drunk. Only a bit. He couldn't really let himself get further than "a bit." He was sure there were a thousand perks to being utterly shit-faced-particularly the part where you didn't remember things-but it just wasn't worth the risk.

Undyne sat down beside him without warning. Sans blinked up at her.

Welp. So much for avoidance.

"Oh, hey," he offered. "Was gonna say hi earlier, but then you put Doggo Jr. in a headlock. Figured I shouldn't disturb the fun."

"I love dogs," she said, chuckling and pumping a fist. "They really know how to throw a party!"

"Heh, yeah. Real _party animals,_ right?"

She snorted. "Dog-gone crazy, half the time!"

"Heh."

"So, uh…how _you_ doing, punk? I've been meaning to talk to you for awhile now."

He grinned at her. "Uh oh. The boss fish wants to talk? I must be in trouble."

"It's not like that!" She glared at him. "Wait, actually it is like that! I heard about how you skipped out on your shift yesterday. Don't think I didn't!"

"Yeeeaaahh…" Sans shrugged languidly. "Wasn't feeling well, so I went home. Already talked to my supervisor about it. All's forgiven."

Undyne huffed in disdain, but didn't press. She sipped at her own drink, which appeared to just be tea.

"How _are_ you doing, though?" she asked at length. "Since that whole…?"

She waved her free hand vaguely. Sans finished off his drink and thought about flagging Grillby down for another. He shouldn't, but he wanted to. Being drunk would thoroughly help this conversation.

"Since what? Oh-the thing with our little sparring match? Oh, yeah, I'm good. Forgot all about it, actually."

She raised her eyebrows at him. "Yeah?"

She sounded like she didn't believe him for a second.

"Yep."

"Well…I wanted to apologize again. And let you know that I'll never do that to you again, not unless you're absolutely okay with it."

Sans propped his chin on his hand, looking as casual as always. He was starting to think he should have just gone home with Papyrus.

"Yeah, I got that the first couple times you said it. Like I kept saying, it's not big deal." He let his eyesockets drift closed, as if the discussion bored him. "I'm fine with it. My soul just had a weird reaction, that's all. Bet you could turn me green now and nothing dumb would happen this time."

That was stupid. He shouldn't have said that. Undyne would never-probably-but it wasn't like him to tempt fate.

He could feel her staring at him. That one eye of hers was probably trying to bore into his skull.

She sighed and he heard her shift on the stool.

"Ugh. You say that, but I'm still not turning you green again. You're a really hard guy to read, you know that?"

"Nah." He drew the word out, almost turning it into a sigh. "I'm a simple guy."

"Papyrus is worried about you." Her voice was sharp. "He says you haven't been sleeping."

Sans kept his eyesockets closed and his expression neutral.

When had Papyrus noticed? Why hadn't he said anything? And why did he have to keep _talking about him_ to random people?

"Well, that doesn't sound right. Have you _met_ me? I'm a regular sleepybones, heh." He shifted so that he could prop his chin in both hands, as if he might fall asleep right there at the bar. "I slept like twelve hours yesterday. He'll tell you."

"Sans. Do you know what…PTSD is?"

It was such an unexpected question that Sans opened his eyesockets, frowning in the direction of Grillby's back wall.

"Uhh, an acronym?"

Undyne rolled her eye and groaned, looking ready to dump the remainder of her tea on Sans's head.

"Heh, I'm kidding, I'm kidding. It's, uh. Like what happens to guards or soldiers when a really bad fight happens. Right? They see some kind of terrible fight and it affects them mentally."

Gerson had mentioned something like that once, while he was telling one of his more solemn war stories.

"Right." Undyne looked away for a moment, and reached up to touch her eyepatch. "But it doesn't just happen to people in combat. It can happen to pretty much anyone who's seen some bad shit."

Ah. Now he knew where she was going with this. And where she was going was absurd.

"Jeez. Come on." He resisted the urge to just get up and walk out without another word. "I don't have-"

"Hey!" She turned suddenly in her stool to face him, grinning wide enough to show all her teeth. She pointed at her eyepatch. "How do you think I lost this? What do you think happened?"

"Uh." It was getting harder to resist that urge by the second. "I…don't know?"

"Come on, I bet you heard at least one of the stories! The other guards spread all kinds of 'em around! I think my FAVORITE is that I lost it while fighting a bear! Like, an actual bear, not a bear monster, with the giant claws and everything? Grraaahhh! How badass would that have been?!"

"Uh. Heh." He folded his arms on the bar and gave her a tentative smile. "I mean, I guess I always figured you'd lost it in a fight or something? It's, uh…you know, not the kind of thing you just bring up. When you're trying to be polite and all."

She laughed. "Politeness! Who needs it! But yeah, that sounds about right! Some kind of epic fight against a wild criminal or a _human!_ Do you wanna know what _really_ happened?"

"Not really?"

"Well, I'll tell you. You're lucky! You're one of, like, three people who's gonna know the truth!"

"Okay…"

There was no escape from this, was there? For all that she said she didn't care about politeness, he was pretty sure she would punch him in the face if he just up and walked away right now.

Or turn him green again. Wouldn't that be hilarious.

"So, I was eight years old, in second grade. You remember how in second grade, they'd make you do the Waterfall Walk?"

"Oh…right, I remember. Yeah, you walk through Waterfall and read all the history plaques. Asgore himself started it. Said kids should walk the same path our ancestors did." He grinned a little. "Heh, I hated all that walking. I snuck away from the group and just went back to the ferry. Read a book till the class returned."

"Pfft! Reading a book! I didn't know you were a nerd like Papyrus!" Undyne laughed. "But I had the same idea! History is so BORING, you know? Once we got past the Wishing Room, I was out of my mind! So I snuck off and went exploring. Picked up a stick and started swinging it at water sausages, pretending I was swordfighting humans! Ha! I was a real hothead!"

"Heh, 'was,' huh?"

"Shut up! Anyway, I was having a great time, exploring on my own, fighting humans, finding cool bugs…I figured I'd just go back and rejoin the group when they doubled back, before anyone could notice I was gone. I knew Waterfall like the back of my hand, anyway!"

Undyne paused. Her grin turned wry.

"But then there was a cave in."

Sans watched her. Undyne took a slow drink of tea.

"It wasn't a big one," she continued. "They happen in Waterfall all the time, and I grew up there, so I was used to them. I was just in some little side cave when part of the ceiling came down. Right on top of me! Pretty bad luck, right? It wasn't even the first cave in I'd been in! I'd gotten trapped by one earlier, I think I was six maybe? And that one had been bigger. But this one, it was just bad luck. It was this whole vein of crystal that came down and, heh-those things are way sharper than they look! It was like getting hit in the face with a whole pile of glass."

Undyne paused again for another sip of tea. Sans was silent.

"Sliced up my eye. I just started screaming. But I was all alone, right? I'd left the class behind, and no one was around. So I'm stuck in this hole, covered in rock and crystal, freaking out cause I can't, you know…see anything, and I'm not strong enough to move the rocks. I'm, uh…"

She paused and tilted her head at him curiously.

"I mean, you're a skeleton, so I guess you don't really know what it's like, having skin and all that. There's just something…really fundamentally _freaky_ about feeling bits of crystal in your eyeball."

"Jeez…" Sans couldn't help a bit of a shudder. "I mean…I've had things get into my sockets before, and it's really disturbing, but that's…that just sounds horrifying."

Undyne grimaced. "It was. Not even gonna lie. I was stuck in there for six hours before anyone found me."

"Shit, man."

"By the time they did, the eye was basically gone. Too late to save it, you know? But I was a tough kid. I bounced back fast, was back in school a week later, showing people my cool new eyepatch and everything. Like I said, I'd been in cave ins before, so it seemed like it wasn't a big deal. I thought I was fine. But I was having nightmares. I'd make up excuses not to go to the Wishing Room. I couldn't look at any of the crystals anymore. Every time I saw one, I could feel the shards in my eye again. I started just avoiding the parts of Waterfall with lots of crystals entirely. I felt so stupid and ashamed. Like, why was I afraid of some dumb rocks? Why did I have to wander away from the class anyway? Why did we have to go on the stupid field trip at all? Ha, I started blaming Asgore! I even broke into the castle and tried to fight him in revenge! Heh, that guy…he's a really great guy. I didn't land a single hit on him, but all he did was ask if I wanted to know how to fight! And then he started training me, personally! Me, just this random fish monster from Waterfall! It felt like my life was starting to get better, you know?"

She chuckled to herself and finished her tea, then set the mug down and pushed it away.

"But then it was two years later, and I still couldn't look at crystals without breaking into a cold sweat. And then one day, I was coming back from the Temmie Village for some reason and I got…stuck. In that really dark cave, you know the one. With, haha, with all the light-up crystals? There I am in the dark, and there's this crystal in arm's reach that will light up if I touch it, but I have to _touch it,_ you know? And the dark felt like being trapped again. Felt like the world was closing in around me. Like teeth or something. I just panicked. One of the Temmies found me and brought me to the next cave over. That's when I finally admitted there was something wrong with me. I realized I couldn't live like that anymore. So…I got better. It took forever, but I got better."

She fell silent, turning around in her stool and looking out at the other partygoers. There weren't many left. It was mostly down to the Grillby regulars.

Sans was quiet, waiting. That couldn't be it. But Undyne wasn't continuing.

"…How?"

"How what?" Unydne said without looking at him.

"How did you…get better?"

"Oh. I trained a lot!" She grinned at Sans. "I trained and trained! I made myself go near crystals, bit by bit until I could touch them and be near them. I talked to people. Mostly my mom, Asgore and Gerson. I told them what was going on and they helped me."

Training. And talking to people. It sounded so simple. It couldn't possibly be that simple. Not that it mattered. It wasn't like either option was available to Sans. Training sounded an awful lot like exercise. And talking about it was out of the question.

Ah…she'd gotten him. That was clever of her. Now here he was, thinking of in the context of his own experiences. Here he was almost admitting that he was, what, traumatized? Traumatized like a kid who had been buried in a cave in and experienced the horror of losing a body part? Traumatized like Alphys was after losing her father in such a _fundamental_ way? As if it was even comparable. But still. Very clever.

"Heh, well. Good for you. It would suck if you couldn't look at crystals anymore. They're the only stars we have down here."

"Right? Well, it wasn't easy. It took a few years. I'm fine now, but some monsters aren't so lucky."

She gave him a very obvious, very pointed look. He matched her gaze.

"Well. I'm happy for you. Not, uh, not sure why you decided to tell me all that, though."

She groaned loudly and threw up her arms.

"Oh my _god,_ don't be so _dense!_ You're doing it on purpose! I'm trying to help you here!"

"Except I already told you I don't need help. I'm _fine._ As fine as you are."

"Sans. Listen to me." She turned to face him and got control of her voice, her face turning very serious. "I know panic when I see it. When I turned you green, I saw _myself._ I saw me, trapped in the dark cave again. It's the same thing I see in some of my guards sometimes. The same thing I see in…" She hesitated, eye flicking to the side before she continued. "I've been thinking about it ever since. Something bad happened to you, right? And when I turned you green, it reminded you."

Sans gave her an easy grin.

"Undyne, you couldn't find two more different monsters than us in the whole Underground. Not even if you tried."

She was getting angry, but somehow she was keeping her composure.

"Did someone turn your soul green before me?"

Sans's soul was humming in his ribcage. "Pfft, how would that even be possible? There's no other monster in the Underground who can use green magic the way you can."

She was quiet for a moment, her one eye searching him. He was calm. He was casual. He was fine, just the same old Sans. He gave her absolutely nothing.

"…True. But I don't know. It just doesn't feel right."

He said nothing, his expression not changing a fraction, even though his soul felt ready to burst. Sweat was prickling along his skull but he ignored it.

"You were saying 'stop.' Over and over. Listen, I know this sort of thing is hard to talk about, but talking about it helps. I promise."

She promised.

God, he hated promises.

He should say something. He needed to say something. Needed to tell her how off-base she was. Needed to say _anything at all_ to get her to stop.

"Did someone hurt you, Sans? "

Sans got to his feet. He yawned.

"1 HP, remember? It's not possible for anyone to hurt me." He shrugged as casually as he could manage. "Anyway, it's been great listening to you theorize about me and tell stories and all, but I think I'm all partied out. Got four jobs now, so I'd better enjoy maximum sleep while I still can, heh. Tell Grillby to put it on my tab."

She sat upright. "What? Don't run away!"

"I never run if I can help it."

She was getting to her feet now. She was actually _following_ him.

"God, you're difficult! I wish I could just punch you!"

"Heh, boy, if I had a G for every time someone said that, this woulda been _my_ retirement party."

He stepped out into the cold and snow. Sans at last had an excuse to pull up his hood, obscuring his face. She was still following.

"Sans. Wait." Her voice was commanding, sharp. The kind you couldn't help but listen to, the kind she probably used when she was ordering her guards around.

Gaster had sounded like that sometimes. Sans stopped and looked back at her, hoping that all she could see of his face was his grin.

"I get it. You don't want to talk about it. That's fine. It's not like we know each other that well, so I get that you don't want to tell me anything."

"Heh. That, and…" Sans chuckled a bit, tiredly. He'd remembered something. "That and, in my experience, it's real bad news to try and be friends with your boss."

She snorted, but didn't quite laugh. She folded her arms, shivering a bit from the cold, and sighed with an air of finality.

"Just answer me one thing, alright?" Her yellow gaze turned dangerous. "Just tell me if there's anything I can do about it. Tell me if there's…any _one_ that I should go have a _friendly chat_ with."

He stared at her. Part of him wanted to just be…mean. Tell her that all she was doing was trying to clear a guilty conscience by passing the blame to someone else, whether it was true or not. Tell her that she meant nothing to him, and he meant absolutely nothing to her-that he was just her friend's weird brother. That she was wasting her time even bothering to be concerned. And what was she going to do, anyway? Go try to arrest the Void?

The image was so hilarious that he almost started laughing. He could see it now, Undyne standing above that churning dark, yelling obscenities and shaking a pair of handcuffs.

But she was like Papyrus. A good person. A far better person than he was.

Not like it was hard.

"…Nah. Sorry, Undyne. I know you're trying to help, but…there's nothing you can do. If anything…if anything did happen, it was a long time ago. And if, uh, if there was anyone you could have that 'friendly chat' with, they're. Long gone."

She watched him, eye narrowing.

"Everyone's got baggage. Just gotta keep carrying it, right? I'm a pretty little guy, so mine's lighter than most."

He wasn't the one who had lost an eye. He wasn't the one who had lost a father. He wasn't the one who had been shattered across space and time. He wasn't the one who had died. He was alive. He was lucky. He had _survived._ What right did he have to even _feel_ bad about any of it?

He tugged his hood a little higher and turned away from her.

"Don't tell Papyrus about this, okay? He worries too much about me already."

"I won't. But _you_ should. He's your brother. You should talk to him."

"Heh." He started walking away. "I'll see you around, boss."

This time, she didn't follow.

* * *

"I WAS NOT FINISHED."

It was the basement laboratory as it had once been, but broken into pieces. Chunks of building floated above an abyss of glitching, rainbow static. The air was filled with white noise.

Gaster had him pinned to a section of crumbling floor, his form obscured by shadows and torn reality. There had to be dozens of hands, each of them holding Sans down, gripping his limbs, his neck, his spine. Two hands held his skull, a thumb digging into his left eyesocket, keeping it pried open.

Sans couldn't move. But that was nothing new. Sans was watching the sky. It was violently bright, a dome of gray and white fuzz. Occasionally a bolt of something red cut through the gray, like lightning, and the whole world would shake.

"DO NOT INTERRUPT." The thumb dug deeper into his eyesocket, until it hurt. "YOU SHOULD KNOW BETTER."

"Right." His own voice sounded empty. "Sorry."

Two dreams inside a week. That only happened when Gaster was angry. At least the rest of the week had just been normal nightmares.

"YOUR AVOIDANCE. YOUR DODGING. YOUR COMPLACENCY. WILL BE YOUR UNDOING."

"Okay." Sans watched another arc of glittering red. "How about you just say what you wanted to say. So I can wake up. This is annoying."

All of the hands tightened. Sans tried to squeeze his eyesockets shut, but Gaster kept the left one pried open.

"NO. NONE OF THAT. YOU NEED TO SEE."

"Don't want to."

"FOOL." There was a hand clawing around inside his ribcage, questing. "YOU DO NOT. HAVE A CHOICE. NOT WHEN YOU HAVE THIS."

Two fingers pried his left eyesocket open wider, until Sans felt the bone creak.

"Stop."

"YOUR WILL HAS WEAKENED." The hand in his ribcage closed slightly, as if trying to grip his soul. "COULD TAKE YOU NOW. TAKE IT FROM YOU. ALL OF IT. ALL OF YOU."

"I think you're lying." It was astonishing, really, how calm his voice was when the rest of him felt like coming apart. "I think that wasn't actually ever an option. I think if it was that easy, you would have done it years ago."

"YOU HAVE NOT MADE IT EASY. YOU MAKE NOTHING EASY."

"I think all of this was pointless." There was another slash of red in the sky, and this time it bled across the gray, turning it dark, like a stain.

"I think you were drowning," Sans continued as the sky went darker and darker. "You were drowning and climbing on the only thing that would keep you above water. But you were always going to drown. All this time, I thought I was…protecting something. Like somehow I was preventing you from, I dunno. Possessing me like some kind of weird ghost and wreaking havoc on the real world. But that was never possible, was it?"

Gaster didn't answer, but the hands were loosening their grip. Sans grinned as the sky turned blood-dark.

"Thought so. All this time, and there was no point to any of this. Any of the shit you put me through. Heh. That's hilarious."

The hands released him. The mess of static that was Gaster withdrew and seemed to regard him. Sans breathed.

"WE BEGIN TO SEE."

Sans sat up slowly.

"You said you wouldn't hurt me anymore. But you're always going to hurt me, aren't you? Like crystals in an eye. Maybe you'll never do it again. But it doesn't matter. No matter how far past any of this I get, no matter whether I fix everything or not, this is just…this is how it's going to be, isn't it?"

"WE BEGIN TO SEE."

Sans drew his knees up to his chest. They sat together on their floating piece of dreamworld in silence. The abyss below was beginning to darken as well as the red crept further and further.

"Look at the pair of us."

"A PAIR OF FOOLS."

Sans snorted faintly. He could think of no better description.

"HAVE YOU GIVEN UP, SANS?"

"No. No, I…not yet. I can still…I have to."

"DO YOU HAVE ANY IDEA. HOW DIFFICULT IT IS. HOW MUCH EFFORT IS REQUIRED. TO SPEAK TO YOU IN THIS WAY? TO FORCE EVEN THE BAREST SEMBLANCE. OF COHERENCY."

Sans was quiet.

"THIS WILL HAPPEN. WITH LESS FREQUENCY. YOU WILL BEGIN TO FORGET. IT HAS ALREADY BEGUN."

Her father. His friend. And he couldn't even remember the name. Sans hugged his knees tighter.

"I don't want to give up."

"WE ARE RUNNING OUT OF TIME, SANS." The static hissed, almost a reprimand. "STOP WASTING IT."

"Heh." Sans pressed a hand to his face, closing his eyesockets. The world was fading. "So it all really was pointless. All of it. _All of it."_

Four years. Four years of nothing.

Sans could remember the exact day, the exact moment that he had realized he wanted to become a scientist. One of the bad days, but not so bad that he couldn't stay awake. He'd sat up in bed, reading like usual. A piece of a book called _Cosmos,_ by a human scientist, just a few water-damaged pages that Sans had dug up from the dump. Pictures, mostly, of stars and nebulae. There had been a lot of words that he didn't understand, but he had known that he wanted to understand them. Had decided to find out what hydrogen was and why it was important. Papyrus hadn't even been born yet. The pictures of things he would never see and the words he longed to understand were all he had.

His whole life. For nothing.

Sans grinned into his hand.

"That's hilarious, too."

"SOMETHING IS COMING."

"Yeah." Sans dug the heels of both hands into his eyesockets, still grinning. Always grinning. "Yeah, I know. Something's coming. You gonna finally tell me what, Doc?"

"AN ANOMALY."

"That's vague."

"LOOK FOR IT."

The dream was starting to come apart, the edges peeling back.

"YOU WILL KNOW IT WHEN YOU SEE IT."

A streak of red bisected the dream. Sans woke up.

He stared at the ceiling.


	11. Mea Culpa

.

 **ENTROPY**

* * *

Chapter 11: Mea Culpa

Warnings: This chapter contains **guns and gun violence** , **child death** , and **misuse of alcohol.**

 _Yeah, Sans never tells anybody anything.  
_

* * *

Once again, there was a human in the Underground.

They'd come through in the night, though how they'd done it was anyone's guess. Sans found tracks-very obviously human tracks-right past his station in Snowdin. He'd gotten to be something of an expert on humans, so to speak. By the time he'd called it in, the human had already been spotted in Waterfall. They were moving fast.

The Royal Guard was furious, none moreso than Undyne, at least according to Papyrus. His special training was on temporary hold while the guards scoured the Underground for the human. Papyrus, for his part, was outright disappointed-both that he had again failed to capture a human, and that the human had apparently gotten all the way through Snowdin unscathed.

"I don't UNDERSTAND IT! My traps should have WORKED!" Papyrus had said that evening as he paced the kitchen. Papyrus only paced when he was truly upset.

"Don't take it so hard, bro," Sans had tried to assure him. "Maybe they're just real good at puzzles."

"That's just IT! All my puzzles were COMPLETELY UNTOUCHED! It's as if the human simply IGNORED them! How could ANYONE ignore a puzzle lovingly crafted by THE GREAT PAPYRUS?"

"Heh. Maybe they're just rude."

Papyrus had paced and grumbled for the rest of the night. Even a bedtime story wouldn't calm him down, and the following morning, it was pretty obvious that Papyrus hadn't slept well. He wasn't the type of monster to become _irritable_ exactly, but he was definitely the type of monster to down four cups of coffee and wake his older brother before six AM.

"Bro, please, even if we had a sun down here it wouldn't be up yet," Sans protested weakly as Papyrus dragged him out of bed.

"NONSENSE! IT IS THE PERFECT TIME TO BE AWAKE! WAKE UP ALREADY, LAZYBONES!"

"Nope." Sans felt himself steered down the stairs. "Mm still asleep."

"We're going to go FIGURE OUT HOW THAT HUMAN GOT PAST US SO EASILY! So wake up! We've got an Underground to defend, Sans!"

Papyrus pressed a mug into Sans's hand and he automatically raised it to his mouth. The coffee tasted burned.

"Mmf. Thought they weren't lettin' you search Waterfall with th' guards."

"They're not," Papyrus said, disappointment creeping into his tone again. Sans was deposited at the breakfast table and he promptly crumpled forward, pressing his forehead to the wood.

"But we are not going human hunting!" Papyrus lifted Sans up and made him lean back in the chair. "We're going to RECALIBRATE OUR PUZZLES! Clearly they need to be MORE DIFFICULT! Sit up straight, Sans! I have breakfast already for you! I might have made too much…"

Sans cracked open an eyesocket to see what appeared to be soggy waffles stacked in a heap on a plate in front of him. The waffles were also covered in spaghetti.

"…Think I'll be okay with just coffee, bro."

"Do you work today?"

"Nope."

"PERFECT! Then we can spend all day on our puzzles!"

"Uh, just remembered I work a triple. In Hotland. But not till this evening, so I should really go back to bed…"

"NICE TRY, SANS!"

Sans just sighed, drank his coffee and resigned himself to his fate.

He fell asleep mid-stride three whole times on the walk out to Papyrus's sentry station. By the third time, Papyrus decided to just carry him on his back, grumbling the whole rest of the way.

"HONESTLY, BROTHER! DO I HAVE TO DO EVERYTHING AROUND HERE? YOU'LL GET ICE IN YOUR JOINTS IF YOU FALL ASLEEP IN THE SNOW! I SWEAR, SOMETIMES YOU JUST…"

His voice faded out and Sans fell asleep again, head resting on Papyrus's shoulder. Sleep came easy lately, even more so than usual. His dreams had quieted, his nightmares had settled. And Gaster was nowhere to be found-not that that was anything new. More often than not, Sans's sleep was empty and silent. If he dreamed at all, he barely remembered it.

Overall, things were pretty okay.

He drifted back in when he felt Papyrus come to a stop sometime later. His brother was still talking.

"…was TRYING to tell her that spaghetti sauce CERTAINLY doesn't need vodka in it! Whoever heard of ALCOHOLIC SPAGHETTI? But SHE kept insisting that it wasn't ACTUALLY alcoholic! Something about heat and I suppose we DO USE A LOT OF HEAT! SO MUCH HEAT! But what does that have to do with whether or not something is alcoholic? And she DIDN'T KNOW! Vodka sauce, really! Honestly, it's just RIDICULOUS, AND MAKES NO SENSE!"

"Mmf." Sans looked up blearily, taking in their surroundings. They were deep in the woods, near one of the old switch puzzles. Papyrus had been working on updating it for the past year.

Sans rubbed at his eyesockets. "Cause ethanol boils at a lower temperature than water. Stands to reason you lose most of the alcohol content if you're boiling stuff with water in it, especially if you're letting most of the steam escape."

"WHAAAAT? SO IT'S TRUE?" Papyrus crouched a little so Sans could slide off. "Wait, I thought ethanol was in gasoline for cars!"

Sans chuckled. Trust Papyrus to know more about cars than he did about alcohol.

"It's in both."

"How STRANGE! Where did you learn this?"

Sans shrugged. Anyone who had ever set foot in a chemistry lab knew what ethanol was, as well as its boiling point.

"I had a _boiling question_ one day and looked it up at the Librarby."

"UGGGHHHH! SANS! IT'S TOO EARLY FOR PUNS!"

Sans winked. "Shoulda thought of that before you dragged me out here, bro."

"And don't call it LIBRARBY just because of that stupid sign!"

"So what're we doing out here, anyway?"

Papyrus put both hands on his hips and surveyed his domain. His domain being every puzzle between Sans's sentry station and Snowdin Town. So most of the forest, in a sense.

"We're going to recalibrate our puzzles one by one until they're completely human-proof!"

"Jeez. All in one day?"

"ALL IN ONE DAY!"

Sans wondered if he could get away with falling asleep again.

"Alright, bro. Whatever you say."

"NYEH HEH HEH!"

Papyrus got to work immediately, while of course Sans took his sweet time. He had put a grand total of one puzzle out here, entirely at Papyrus's request. He'd always had a rather un-monsterlike indifference toward puzzles, completely the opposite of his brother. Papyrus chattered away while he worked, talking about his plans for puzzles, or sharing town gossip, or wondering aloud where the human was and what it was up to.

Sans was trying not to wonder about that himself. The human had to be halfway through Waterfall at this point, if not all the way to Hotland considering their pace. But this one wasn't going to be his problem either. Someone would capture the human or kill it, and then they would have six souls. One away from everyone's goal.

It was a little astonishing when you thought about it. Sans remembered being a kid and learning that the last human-the First Human-to appear in the Underground had been decades ago. No one had seen a human in all that time, and yet in less than ten years, six humans had fallen. What in the world were the humans doing up there?

Sans remembered how adamant Gaster had been that getting all seven souls and breaking the barrier would surely lead to immediate war; a war that monsterkind would absolutely lose. Two more souls and then King Asgore would do it. Absorb all seven, break the barrier, lead monsterkind out into blood and dust and extinction.

If he could just fix the machine, then…

It didn't matter. Besides, maybe it wouldn't go like that. Maybe monsters would return to the Surface, Asgore would decide not to continue the war, and humanity would embrace them with open arms. Maybe it would all turn out alright, like the ending to one of Papyrus's bedtime stories.

Sure.

"SANS! Did you fall asleep AGAIN?!"

"Huh?" Sans looked up. Seemed he had paused in the middle of unscrewing the cover on one of the pressure plates. "Nah, I'm awake. Just spacing out. Did you say something?"

Papyrus gave him A Look and heaved an exasperated sigh.

"I was TRYING to tell you that I had an idea for how to make this puzzle better, but CLEARLY you would rather sit around and BOONDOGGLE!"

Sans grinned. "Don't you mean _bone_ doggle?"

Papyrus threw a handful of snow at him. Sans chuckled as he dusted flakes off his skull.

"But nah, let's hear it. Your idea."

"Well…I was thinking, WHAT IF! Instead of pressing every OTHER plate on this one, the solution was that you had to press EVERY plate in a specific PATTERN? That way there is ONLY ONE correct solution! Or do you think that would be TOO DIFFICULT for a human? It has to be FAIR, of course! THE GREAT PAPYRUS IS ALWAYS FAIR!"

Sans gave a thoughtful nod. "Huh. Kinda like a maze?"

Papyrus's expression brightened. "Yes, exactly! And there could be SYMBOLS to give you a hint of the pattern! And maybe SPIKE TRAPS!"

"You could probably swing the symbols part, yeah." It wouldn't even be too hard. Just a bit of rewiring.

"I also had an idea for an electricity maze!" Papyrus swung his fist skyward in excitement. "And if they touch the edges…or make a misstep…ZAP!"

"Pretty good idea, bro."

"OF COURSE IT'S A GOOD IDEA! IT IS AN IDEA FROM THE GREAT PAPYRUS, AFTER ALL!"

"One at a time, though. I bet you could turn the one near Doggo Jr.'s station into a maze. Run a current through the switches they're not supposed to step on, something like that. This one makes more sense for the symbol idea. Just switch out the plates for some of those new display screens…"

"And then you press them in the right sequence! YES! IT IS GENIUS!"

It wasn't a difficult task, but it was very involved. Rewiring a series of old, mostly-frozen pressure plates required focus, and if Sans was focusing on this it meant he wasn't focusing on anything else. Which was always the bonus whenever Papyrus dragged him out here for puzzle work. It meant he didn't have to think about anything but the task at hand. He had found himself needing distractions more and more often lately.

Plus it was nice to help his brother, even if it meant being awake at ungodly hours and spending the entire day out in the snow.

Creating the maze was one thing, but swapping the outer plates for ones that could display symbols like Papyrus wanted was another thing. They didn't have any new plates on hand, so that would have to buy some and install them later. In the meantime, there were other puzzles to work on. Now that Papyrus had gotten the symbol-swap idea into his head, he wanted to apply the same logic to all his other puzzles.

The old puzzle near Doggo's station was much trickier. It wasn't as simple as just running a current through some of the tiles, since there would be no way to control the voltage. It would probably just kill anyone who made a mistake while attempting to solve it, and Papyrus certainly wasn't having that. Papyrus sat down with a notebook and got into problem-solving mode while Sans went to say hello to Doggo.

Doggo was outside his station, nervously smoking dog treats and squinting into the forest.

"Sup, dog?"

Doggo unsheathed his sword in one fluid motion and whirled on Sans. Sans sidestepped automatically, even though Doggo halted before he could actually attack.

"Sans! I told you to not to sneak up on me anymore!"

"Your reactions are kinda priceless, though," Sans admitted with a careless shrug. "Kinda figured you'd heard me coming. Or at least heard Papyrus."

"You _know_ I have a hard time seeing you," Doggo grumbled, resheathing his sword. "If you'd just move more! You're so creepy! Ugh, at least your _brother_ moves a lot. Anyway, I was distracted…"

"Yeah? Did a mailman run by?"

"Very funny. There's a weird smell in the forest." Doggo turned back to the trees, ears twitching. "I went to look for it, but nothing's moving, so I can't see what it is. Whatever it is, it's making me nervous."

Sans went to stand next to him to see where he was looking. There wasn't anything particularly interesting or out of place.

"I don't see anything either. How far in is it?"

"That's right!" Doggo looked in Sans's general direction with a grin. "With my nose and your…eyes…? Or whatever? We could find it! Follow me."

Doggo started off into the woods without waiting for an answer, dropping the smoldering end of his dog treat into the snow. Sans shrugged to himself and followed. Doing odd-jobs for the dogs hadn't really been on the agenda today, but hey-distractions.

It was about a five minute walk, though Doggo stopped now and then to sniff the air or the ground, with the occasional muttered "this way" or "weird smell." His tail was raised and still and his ears were pricked. He really _was_ nervous, even by Doggo's standards. The guy was paranoid even on a good day.

"It's around here," Doggo said, stopping at a small clearing and putting his hands on his hips, frowning at nothing. "I can't pinpoint it. Take a look around and see what you can find."

"Alright. But if it turns out to be another squirrel that got underground, I'm not helping you chase it."

"I wouldn't need a skeleton's help to chase squirrels!"

Sans poked around the clearing. He had been here before while scouting for safe places to practice magic, but this one had never worked out. It was too small and too close to both Doggo's and Papyrus's stations. There wasn't much here-just more snow and some ferns. Though as Sans explored, he noticed that the snow had been disturbed in some places. There were monster tracks and a few blue and white Snowdrake feathers.

"Found some feathers. I guess the teenagers must come out here."

"Ugh, I'm always telling them not to come here! There's plenty more forest to do dumb teenager stuff in! But I know what Snowdrake smells like, and what I'm smelling isn't Snowdrake. Look harder! Make yourself useful for once!"

"Hey, don't worry, I'm working my eyesockets to the _bone_ here."

Sans followed a short trail of tracks and feathers to a spot where the snow was kicked up, as if the teenagers had been having a mock battle or something. There was something half-buried in the snow, and Sans stooped to pick it up. It was a small metal cylinder, about an inch long and brassy. The cylinder was hollow, but capped on one end.

"Huh."

"What? Did you find something?"

"Yeah, it's some kind of…"

He was crouched, but even then it was hard to see what else was in the snow. It was gray, almost invisible against the white, and spread across the surface of the snow in piles.

Sans had never actually seen any in real life before, but he knew what it was. His marrow went cold. No wonder the human had gotten through Snowdin without anyone noticing.

"There's monster dust here."

Doggo didn't answer right away.

"…What?"

Sans stood up and stepped back, closing his hand around the metal cylinder. He slid his phone out of his pocket.

"Can you do me a favor? Can you go tell Papyrus that something came up and he needs to go home? Tell him I'll meet him back there. Don't mention the dust, understand? I'm gonna call Undyne."

Doggo whined under his breath.

"R…Right. I'll do that."

Sans dialed Undyne's number as Doggo took off. So much for a day of distractions.

"Hey, Undyne? You'd better come out to the Snowdin Forest. Near Doggo's station. I think that human killed someone."

* * *

Undyne didn't keep Sans for too long-just long enough for him to give his report and hand over the strange metal cylinder. Unydne wasn't sure what it was either, but all the dogs agreed that the cylinder smelled acrid, very distinctive. They might be able to use the scent to track the human, but that was assuming that the human was the one who had left the cylinder behind.

"Someone else found monster dust in Waterfall about an hour before you called me," Undyne said grimly. "I've still got a team there, so I'll tell them to look for more of these cylinders. Best Dog's on her way to assist, since she's got the best nose in town."

"What about the Snowdrake's family?"

Undyne bared her teeth and rubbed at her forehead. "That's my responsibility. I'll find them while my teams are working. I've got RG 01 and RG 02 guarding the main path to the Core, so even if the human has gotten that far, they _definitely_ won't get any further. They're two of my best."

"Jeez. This might be the worst one yet."

The human with the orange soul and the one with the blue soul had both managed to kill one monster apiece, but this human was already at two. And at least one of them had been a teenager-a kid. Sans knew most of the Snowdrakes in town. He even worked alongside one of them, a guy who did stand-up at the MTT Resort. He was constantly talking about his son; Sans was pretty sure the kid was too young to have been out here in the woods like the rest of the teenagers, but you never knew. It wasn't like monster dust had identifying features.

Sans couldn't imagine what it would be like to lose a child. He remembered losing Papyrus in Waterfall one time while they were coming back from a dump run. Papyrus had just gotten lost and Sans had eventually found him safely, but he remembered panicking the entire time. Papyrus must have been about six or so. It wasn't the same thing. Somewhere in town were two Snowdrakes who were wondering where their kid was, who were probably panicking, who were about to get the worst news of their lives.

Undyne was staring at him.

"You okay, Sans?"

"What?" He blinked up at her. "Yeah, I'm fine."

"I know it's not easy, uh…finding monster dust like that."

"I'm fine, Undyne. Worry more about that poor kid's parents."

Undyne sighed. "You can head home now. We'll take it from here. What're you gonna tell Papyrus?"

He shook his head. What _was_ he going to tell Papyrus?

"I'll think of something."

Sans didn't go straight home. He swung by Grillby's first to calm his metaphorical nerves, as well as to check if the Grillby's rumor mill had started up yet. True to form, several of the regulars were already chattering away, muttering about some kind of unknown tragedy in the woods. Sans didn't say a word-he just got his drink and moved on. He went to the Snowdin shop after that to get Papyrus some Cinnamon Bunnies as a preemptive apology. He had a feeling that he would need them. It also gave him a bit more time to think of a good story.

Sure enough, Papyrus was pacing the living room when Sans got home.

"THERE YOU ARE, BROTHER! WHAT IN THE WORLD TOOK YOU SO LONG? DOGGO SAID YOU WOULD MEET ME BACK HERE, AND THAT WAS AN HOUR AGO!"

"Sorry, bro. I figured I'd get you some buns to make up for having to leave your puzzles early." Sans set the paper bag down on an endtable.

"NOTHING COULD POSSIBLY MAKE UP FOR HAVING TO ABANDON MY PUZZLES," Papyrus lamented, eyeing the bag. "BUT I SUPPOSE…Cinnamon Bunnies are a start. SANS, WHY DID I HAVE TO ABANDON MY PUZZLES? Doggo looked DOWNRIGHT AFRAID! And it couldn't possibly have taken you a WHOLE HOUR to get Cinnamon Buns!"

"Yeah, I stopped at Grillby's on the way." Sans gave his most easygoing of shrugs.

"UGH, SANS! YOU SPEND WAY TOO MUCH TIME THERE! Couldn't you at least have come home FIRST so you could TELL ME WHAT'S GOING ON?"

Sans shrugged again and helped himself to a bun. "Not much going on, bro. The Royal Guard thought there might be another human in the woods."

Papyrus's eyelights brightened.

"ANOTHER HUMAN! FINALLY, THE CHANCE I'VE BEEN WAITING FOR! Oh no, if only I'd had enough time to finish recalibrating my puzzles! BUT NO MATTER! IF I HEAD OUT THERE NOW-"

"Heh, hold on, bro." Sans let a bit of a chuckle into his voice to sell it better. "I said they _thought_ they found a human. Turns out it was just some evidence left behind by the original human. Just some stuff they left in the woods, that's all."

Papyrus slumped with a dramatic sound and grabbed the bag before Sans could steal any more buns.

"You could have said that part SOONER, you know!"

"Don't worry, bro. You'll catch a human one of these days." Sans paused, considering the bits of cinnamon sugar dust stuck to his phalanges. "But, uh. Hey. If you ever do end up seeing a human…be careful, okay? They might not be what you expect."

"OF COURSE I WILL BE CAREFUL, BROTHER! THE GREAT PAPYRUS IS ALWAYS CAREFUL!"

Sans looked up at him, dusting his hands off. He wanted to tell Papyrus that he was being serious, maybe even break his personal rule and make Papyrus _promise,_ but…that would just make him suspicious and worried. There was no way to keep the truth about the Snowdrake's death a secret for long, not when the kid's parents lived in town and not with the way the townsfolk gossiped. But if Sans could spare Papyrus the full reality of what had happened, he would.

So instead, he grinned.

"I know you are, bro. Anyway, uh. They're looking around the area for more evidence right now, so they're probably not gonna let us go out there again today. We can just chill at home the rest of the day."

"NONSENSE!" Papyrus snarfed down a bun. "WE CAN WORK FROM HOME! We might not be able to recalibrate our puzzles from here…BUT WE CAN PLAN! I have all sorts of ideas!"

Sans chuckled a bit for real this time. "Aww, jeez. Alright, bro, whatever you want."

He didn't sleep too well that night. The next day, he had two back to back shifts at both Hotland stations, which was nice in that it at least provided a bit of a distraction. Sans had an extra cup of coffee that morning. He needed to be alert-just in case.

Hotland was like a disturbed anthill. The laboratory was on lockdown, and the main road to the Core was dotted with checkpoints. All of the puzzles from the Waterfall border to New Home had been recalibrated, which made traffic a complete nightmare. Royal Guards were everywhere, checking on the sentries every half hour or so. Between that and all the monsters constantly coming up to ask Sans what was going on or for the latest news, Sans ran through his entire repertoire of news-related puns before his first shift was even over.

And just as Sans had feared, Papyrus called him while he was on his way to his second station.

"Sans?" Papyrus's voice was quiet on the phone. "Have you heard?"

"Well, we don't have ears, so it's kind of a toss-up whether I hear things or not, heh."

He heard Papyrus sigh and kept walking.

"There's some bad news, brother. It sounds like the human might have…maybe…possibly…hurt someone? In the woods outside Snowdin? Right near my switch puzzles?"

"Oh." Sans made himself sound surprised. "Jeez, bro. That's, uh. Jeez."

"You know that Snowdrake, Snowball?"

Sans bit back a curse. He'd met Snowball a few times before. She was one of those teenagers who was a brat while with her friends, but nice and sweet when she was on her own with no one to impress.

"Yeah, I've met her."

"It seems she-well! At least what the guards are telling me is that she's…that someone found…"

"It's-it's okay, Papyrus, you don't have to say it. I gotcha. That's awful, bro. Are her parents okay?"

Papyrus made a sound like he was clearing a nonexistent throat. "I don't…really think they are? They are very upset."

"Understandable." Sans paused as he waited in line for one of the steam vent launchers. "Uh. Are _you_ okay, bro?"

"Of course I am, brother! I just…feel very bad for her parents! Losing a loved one is-ANYWAY! I AM CERTAIN THAT THIS WAS ALL A TERRIBLE ACCIDENT! No one would ever hurt someone like that intentionally, especially not a child! Right, Sans?"

"…Right, bro."

"I can't…help but feel a little bit responsible, though?"

"What?" Sans frowned. "Come on, that's silly. How could you be responsible?"

"Maybe…maybe if I had been there to talk to the human, I could have convinced them not to do violence! Maybe they just needed someone to talk to? Or maybe they just needed a really good puzzle! Maybe that's also the reason they skipped every single one! Perhaps the GREAT PAPYRUS'S PUZZLES JUST…weren't great enough! I will have to work extra, EXTRA hard at recalibrating them and making them PERFECT! So this never happens again!"

Sans was starting to wonder if maybe he could just call out of work and go home. Papyrus absolutely should not be alone right now. He had a tendency to stew when left to his thoughts, something the brothers had in common. But the situation being what it was, Sans had a feeling that they would actually fire him if he tried to skip sentry duty today. Neither of them could afford that, and if the human made it through Hotland while he was gone, Sans would be to blame.

"Papyrus, you…can't think like that, okay?" Sans hopped the steam vent and continued once he had safely landed. "It's like you said, it was an accident. That means it's no one's fault. So don't go blaming yourself, alright? No one could've seen this coming."

There was a long pause. Sans didn't make a sound, soul humming a bit while he waited. The idea that Papyrus was blaming himself when this was all some random human's fault bothered him to no end. Even if it was an accident, the human was the one at fault. People were responsible for their own actions. Intent might mean a lot more to a monster than it did to a human, but it still wasn't everything.

"You're…you're right, of course! THIS IS NO TIME FOR THE GREAT PAPYRUS TO GET DOWN ON HIMSELF! This is a time to make sure Mr. and Mrs. Snowdrake have everything they need! AND ALSO A TIME TO BE RESOLVED! RESOLVED TO DO BETTER IN THE FUTURE!"

"That's the spirit, bro." Sans smiled a little. He had a feeling that Papyrus wasn't completely convinced, but this was better than nothing.

"ANYWAY! I won't keep you from work any longer! I know how much you value hard work!"

That got a laugh from both of them. There, that was much better. Almost like normal.

"Just! Be careful in Hotland today, brother!"

"Always am. I'll see you tonight."

Sans sighed once he had hung up. It was fine. The human was miles away from Papyrus at this point, which was the important thing. Sooner or later, a guard would catch them; and if not that, then there was no way the human would get past Asgore. Certainly not with whatever small amount of LOVE they had managed to collect from Snowball, and whoever they had killed in Waterfall. In the meantime, Sans just had to get through his shift, then he could go home and make sure Papyrus was doing alright. Papyrus very rarely had to deal with the harsh reality of the world.

That was probably Sans's fault.

Monsters were already lined up at Sans's station for hotdogs, including one or two off-duty guards who had decided to look the other way regarding illegal food sales. Business was always a nice distraction, and it was becoming steadily more lucrative. There weren't that many monster food options in Hotland, and one of the other choices was Mettaton's insanely overpriced resort. Hotdogs were cheap and simple. Perfect for a lunch break.

Once the initial line had dispersed, however, things slowed down until Sans was seeing maybe one monster every fifteen or so minutes. Soon, traffic had died out almost completely. A guard came by to tell him that they had closed down one of the elevators as a safety precaution, which mean that everyone was being redirected to the left side of Hotland. So much for a distraction. Sans settled for just taking a nap, only to be woken up a few minutes later by an angry guard banging on his counter. It was a wiry lizard monster with a frill whose name Sans couldn't remember.

"You're useless!" the guard yelled as Sans rubbed sleep out of his eyesockets. "Sleeping on the job when there's a _human_ around! Are you looking to get dusted?"

"Nah."

"Then act like it! You're already an easy enough target as it is!"

"Okay."

"Or do you want me to report you to Undyne?"

"Nah, but Un- _dying_ for you to go back to your job so I can do mine."

The guard braced both hands on the counter so he could lean forward and hiss in Sans's face.

"Watch your mouth, runt. You think you're so hilarious, but I don't think that human's gonna be laughing too much at your stupid jokes."

Sans grinned and almost wanted to push it, but he was tired. The sooner this guy left, the better. He said nothing.

"You have one job to do. It's very simple! Just stay awake and watch for anything suspicious! If you can't even do that, then what good are you?"

Sans just shrugged. The lizard stood back from the counter and gave a derisive snort, smoothing down his frill.

"Always so casual. You don't take anything seriously, do you? I catch you sleeping again, I'm gonna make sure you never work in the Under-"

"Hey," said a new voice. "Leave him alone."

The lizard turned. Sans blinked and looked past him. Two more monsters had walked up. One was a smaller than average Vulkin, and the second was a species Sans didn't recognize. Maybe related to a Knight Knight, though this one was wearing some kind of wide-brimmed hat that obscured most of their face. They were bundled up in baggy pants and an enormous shawl.

"Excuse me?" the lizard said in a slightly incredulous voice.

The second monster stepped forward and the Vulkin hid nervously behind their back.

"I said leave him alone. You're being mean."

The guard was quiet for a few moments, peering at the monster. Then he scoffed and folded his arms.

"The thanks I get for protecting people." He shot a look back at Sans. "No more sleeping on the job, got it?"

Sans gave him a cheerful thumbs-up and the lizard stalked off.

"Uwa! So tense!" the Vulkin said, emerging from behind the other monster and plodding toward Sans's counter. "Getting hotdogs isn't usually this dramatic!"

"Thanks for that." Sans shot a wink at the other monster, who moved forward with significantly less aplomb. "You didn't have to, though. His hiss is worse than his bite. Plus I technically _was_ sleeping."

The monster made a nondescript sound. "I just don't like bullies." Sans saw a flash of their eyes as they looked up at him and they jerked, startled. "Are you…a skeleton?"

"Sure am." Sans busied himself preparing two hotdogs. "What, you never seen a skeleton monster before?"

"I…guess not."

"They're pretty rare these days!" The Vulkin produced a few coins from…somewhere. "Two hotdogs, please! One for me, and one for my new friend!"

"Oh, no, you don't have to do that. I have money." They started digging around in a pocket beneath their odd, patterned shawl.

"It's okay! I like doing things for my friends!"

"But we only just…" The monster trailed off with an uncomfortable noise. Sans tilted his head, trying to see under their hat, but they looked away. They sounded young.

Sans slid two hotdogs across the counter and took the Vulkin's money before the other monster could protest further. The monster mumbled a thank you and the Vulkin giggled.

"You guys heading home?"

"Yup! L2 is too crowded, so I'm taking the scenic route. But I don't mind, because I met a new friend!"

"I'm trying to go to…New Home." The other monster took a bite of the hotdog and paused. "…Is this really a hotdog? It doesn't really taste like one."

Sans regarded the monster for a moment in silence. The monster looked away again.

"Sure it's a 'dog. One hundred percent guaranteed 'dog. As in, apostrophe-dog."

The Vulkin giggled again. The monster let out a small snort and kept eating their water sausage.

"Uwu! You're so funny, Sans!"

Sans gave an expansive shrug. "I try. Anyway, R3 is clear, and I think the elevator from the hotel is still working. The Core has been totally recalibrated, so I don't think anyone's going through there. Might take awhile to get to New Home."

"Okay."

"Thanks! Come on, friend! I can walk you to the hotel!" The Vulkin trotted off with the hotdog slowing sinking into its crater.

"Oh. Okay…" The other monster gave Sans a polite nod. "Thank you for the food, sir."

"Yeah…no problem."

Sans watched the two of them as they walked away, heading for the next cave over. He looked around to make sure no one else was nearby, then put up his "back in five" sign and got up to follow.

Something was odd about that monster, and he had a feeling he knew what it was.

The next area was a long stretch of featureless cave with a narrow path above the magma far below. It was mostly a maintenance area, with a lot of clanking gears and machinery along the walls, along with the occasional distant lava flow. There was nowhere to hide if either monster looked back, so Sans kept as far back as he could without losing sight of them. He wasn't sure why he was doing this. He should probably just call for a guard, or hell, just leave the whole thing alone. The other monster had been acting nice enough. He was probably wrong. Paranoid or something; had humans on the brain, so to speak.

He paused as the pair of them passed the entrance to a small side cave. He shouldn't be doing this. He didn't _have_ to do this. This wasn't his responsibility, not really. Even if that monster actually was a human, it had nothing to do with him. He was just a sentry. And he couldn't even claim this was out of some concern over Snowball. It wasn't like he had known her all that well.

But if that person _was_ a human, and if he just went back to his station and had a nap, and the human ended up killing someone else…

Would that be his fault? Everyone was responsible for their own actions.

Sans hated responsibility. He was too tired for this. He had already done this twice before, and both times had been some of the worst moments in his entire life. The look of terror on the kid's face in Waterfall; the dawning realization on the teen's face in that alley in Hotland. The color of blood; the way the kid had _forgiven_ him.

Two dead kids. _That_ was his fault.

He couldn't do this again.

Sans stopped and stuffed his hands in his pockets. The two monsters had almost reached the conveyor belts in the room beyond. They were practically out of sight. Sans turned with a sigh and started walking back to his station. It was fine. None of his business, anyway.

He got maybe ten paces before he heard a shrill scream behind him.

It was incredible, really, how bad his luck was.

They were too far away for him to see what was happening, and most of his instincts were telling him to just ignore it and keep going to his station. But there was a distinctly Papyrus-like voice in the back of his skull scolding him for the very idea.

Sans teleported across the whole room and landed near the entrance to the next cave. The path narrowed here, and there was a short wall for him to duck behind for cover. He peeked around the corner and his eyesockets widened. The lizard guard from before was there, sword drawn and already advancing on the unidentified monster. The monster's hat had been knocked off, revealing pale skin and long, yellowish hair on the top of its head.

A girl. A human girl. Older than the blue human, younger than the green one.

Such terrible luck.

The Vulkin was hopping in place and yelling.

"Wait! Don't fight, don't fight! Why are you fighting?"

"Stay back!" The guard held his free hand out toward the Vulkin, spreading his frill. "You need to get out of here. That thing isn't a monster, it's a human! I knew it…I had a feeling there was something wrong…"

Sans shifted his position as the lizard circled his way toward the human, and the movement caught the lizard's eye. His gaze flicked over toward Sans and he hissed in surprise.

"Sans? What are you-? Never mind!" The lizard folded both hands over the hilt of his sword and focused all his attention on the human. "Sans, you and that Vulkin get to safety! Go call the guards, tell them the _human_ is here. I'll hold them off. Hurry!"

"Y…Yeah." Sans stepped out from behind the wall. The lizard folded his frill and charged at the human, sword flashing light blue as he swung. The human let out a yelp of fear and dove out of the way.

"Wait! Wait, stop!"

"Come on." Sans put his hand on the Vulkin's back, trying to steer it away. "We gotta get outta here."

The Vulkin didn't budge. "But that's my friend! They can't be a human!"

"Leave me alone!" the human yelled, voice high and frightened.

The Vulkin shifted as if to rush to the human's aid. Sans cursed under his breath, curled his fingers against the Vulkin's stone body and teleported them both all the way back to his station.

Sans let go as soon as they landed to avoid the lava sloshing out of the Vulkin's crater.

"Wait, I'm-huh?" The Vulkin looked around. "How did we get here?"

"I took a shortcut. Listen, go to the elevator and push the emergency button, okay? That'll get guards here."

"But my friend…" The Vulkin sniffled, lava tears starting to trickle out of its eyes. "I don't understand. They were so nice! How could they be a human?"

Sans shook his head, feeling a bit dazed. "I don't know. Just-"

There was a violently loud _crack-bang_ from the direction of the conveyor belts, almost like stone crashing against stone. Sans froze. The Vulkin flinched. The echo rushed along the cave and then died out.

"Go…go call for help, alright?" Sans said, staring off down the cave. It was too far away to see what was happening.

The Vulkin warbled in fear and took off toward the elevator without another word. Sans waited until the Vulkin's back was turned to teleport again.

He landed behind the wall near the conveyor belts again and looked around the corner. The lizard had dropped his sword. One hand was pressed to a spot on his chest. His expression was dumbfounded. The human had her back to one of the belt control structures and was pointing something small, black and narrow at the lizard. She were breathing heavily, eyes wide.

As Sans watched, the lizard crumpled to his knees. He was already going to dust. It was fast, faster than Sans expected it to be. The lizard's chest disintegrated, then an arm. Then the rest of him.

There was a pile of dust and empty armor where the lizard had been standing.

It occurred to Sans that he had never actually seen anyone go to dust before. Gaster had melted and then vanished. The others had simply fallen. The blue human had died in a puddle of red. Humans didn't leave dust.

He couldn't keep a small sound from escaping his ribs. The human spun toward him before he could duck back behind the wall, and the black thing they were holding swung up to aim at his chest.

"Don't move!" The human's voice was shrill, fractured.

Sans didn't move.

"Stay…stay where you are."

"Wait." Sans stared at the black thing in their hands. "Please."

"Shut up, just-just shut up, okay? I don't want to hurt you."

"Okay."

The girl watched him, expression wild, hands shaking. Sans stared right back. He was trembling, sweating. His left eyesocket stung. It was like he could _see_ it, almost as if there were gigantic numbers emblazoned on the girl's shawl. The sensation felt wrong, a sick feeling in his marrow.

"Five," he muttered, forgetting himself. "Five LOVE."

"I said shut up."

"That's a gun, isn't it?" He had seen guns a few times before, mostly in pictures or on TV. "That's what those cylinders were. Shell casings."

"I said shut up!" The girl gritted her teeth and jerked the gun upward, aiming at his skull instead. "I don't want to kill you, but I-I will if I have to!"

"But you…don't _have_ to." Stupid, stupid, he should just shut up, why couldn't he _shut up_ for once in his stupid life? "You didn't have to kill any of them."

"I didn't _want_ to!" The girl's voice broke again. "I never wanted to kill anyone! I wasn't-I wasn't even supposed to be here! I only climbed the mountain because-because-I thought it was the right thing to do, after…I wanted to…"

She was crying.

Sans could teleport. He could just teleport. Human bullets were fast, he knew, but a teleportation was instantaneous. He had been working on his magic, had fine-tuned several patterns of bones and Gaster Blasters. He could just teleport behind her and unleash his best pattern, his strongest attack. Turn her soul blue, bring up a row of bones from the ground, send her rocketing through a sine wave, four-four-four-two pattern of Gaster Blasters to end her if she even survived the first assault.

He could do it. He knew he could.

She was crying.

"It was an accident. I didn't…"

"Nah. Uh. Sorry. I don't think I buy that. Maybe the first time with Snowball, but…then there was someone in Waterfall. Right? And…then this guy."

He didn't gesture toward the pile of dust or even look at it. He had to keep his eyesockets on her, had to watch for any indication that she was about to fire.

"They attacked me. _Everyone_ attacked me. Usually I could run away, or scare them, but…th-the first one was an accident! Like before! It-it was an accident! That…the feathery one in the woods, she-she was being so mean and, and she wouldn't let me run away, and I just wanted t-to scare her, but she…I got angry, I…"

Sans said nothing. The girl sniffled and the gun lowered just slightly.

"Her…name was Snowball?"

"Yeah."

"I'm sorry." The gun lowered further. "I'm-you still get punished even if it was an accident. Right? That's-that's what my dad always-even if it was an accident, y-you can still go to jail. It's a reason, but not a good reason. That's what he said."

"I…I don't know, kid." Sans tried to keep his voice steady. "I just know you…don't get to LV 5 on accident."

The gun was pointed at his ribs again. "What are you talking about?"

"LOVE. It's, uh. An acronym. Stands for 'Level Of ViolencE.'"

She stared at him through her tears and sniffed.

"That's a stupid acronym."

"Yeah. You're right."

"Is that…why I feel so…why it got easier?"

"I don't know. Maybe."

Her gaze lowered until she was staring at his feet, or maybe at nothing at all. But the gun didn't move. Sans had stopped breathing.

There was a long silence, broken only by the child's sniffling and the distant clank of gears.

"I wanted to go see your king," the girl said, lifting her head and looking Sans in the eyesockets again. There was something new in her eyes. Determination, perhaps. "That's why I was going to New Home. If-if you take me there, I won't shoot you."

"Okay. I can do that. There's…a shortcut we can use."

"Good. Then I'll follow you. Just don't try anything funny."

"Heh. You know, I'd. I'd usually have a joke for that." Sans moved very, very carefully forward, edging his way past her, keeping his movements slow. "The shortcut's right, uh, over here. In the wall. I'll just need to take your hand. Okay?"

He glanced back at her. Tears were still streaming down her face, but she was no longer sniffling. Her expression was wary, and the gun was pointed at his back.

"Okay."

She shifted the gun into one hand. The weight almost caused her to drop it, but she kept it raised. She reached forward with their free hand and he took it, very gently. He was still shaking. It felt as though the moment he touched her he would go to dust. But somehow he stayed whole and alive. For now.

"This might feel weird. Just don't shoot me, okay?"

He teleported. He had half a mind to just turn her soul blue as soon as they landed, toss her away and make his escape. She was fast, though. There was a chance she'd get a shot off before he could get away and then, well. Even if he'd had a thousand HP, with that gun he didn't think it would matter.

He let go as soon as they landed. They appeared in the Last Corridor of the castle, near one of the pillars. He had come here a few times; it was the deepest into the castle that he'd ever been, the only place he could picture clearly enough for a shortcut. The corridor was somewhat famous. There was a crack in the ceiling just outside the windows that let in sunlight at certain times of the day, casting the whole corridor in golden light. People called it the golden hallway.

"That did feel weird," the girl said from behind him.

"Thanks for, uh. Not shooting me."

There was a metallic clatter. He looked back and blinked when he saw that she had dropped the gun to the floor.

"I wasn't really going to," she said quietly. "There's no more bullets, anyway."

He stared at her. She was looking out the stained glass windows.

"This place is pretty. It's like a church."

"Kid, what…what are you doing?"

She gave a very small, very shaky smile at nothing.

"There was a lady who said the king would kill me and take my soul. She…she was nice. She almost didn't let me leave. That's true, isn't it? About the souls. Those plaques in the marsh said…said you need seven?"

Sans was silent. A bell was ringing somewhere in the castle. He felt like his ribs were constricting around his soul.

"You were right." She reached up and wiped the tears from her eyes. "I didn't have to kill them. But I did anyway. So…I should face justice."

"That-kid, I don't know if-I'm not a good judge of-he'll kill you. You'll die. You don't-you did something wrong, but-but you don't have to _die_ for it."

Why was he doing this? She'd been about to shoot him. She had killed Snowball, had killed that guard. The guard might have been a jerk, but he hadn't deserved to die. But if he hadn't, then…neither did this kid. LV 5. That wasn't completely irredeemable, was it? If she had been a monster, she would have faced judgment and punishment. Monsters so rarely gained LOVE, and the consequences for murder were severe, but it wasn't like there was a death sentence. How would more killing solve anything?

But she wasn't a monster. She was a human. And this had always been the reality.

"It's the right thing to do." She hugged herself. "I'm sorry. For what I did. Thank you for bringing me here. And for the hotdog. Even though it tasted funny."

He had brought her here. He had brought her to her death, just like last time. The very thing he had been trying to avoid.

"You don't have to do this, you know."

"It's the right thing to do," she said again, starting to cry once more. "How…do I get to the king from here?"

Sans pointed over her shoulder. She nodded and took a shaky breath.

"I'm sorry again. I'm sorry about your friend."

She turned and walked away without another word, leaving the gun on the floor between them. Sans looked down at it. It had been so terrifying a few minutes before. Now it just looked small. Harmless. Empty.

He stuffed his hands in his pockets and lifted his head. Watched the human's retreating back as they stumbled forward. They'd called it justice. All at once, the word felt like it meant nothing.

Sans watched until they left the golden hallway. He heard a door slam at the other end. Then he looked out the window. Light was filtering through the unseen crack in the ceiling, spilling light into the corridor. The pillars cast long, stark shadows.

"Beautiful day out."

* * *

Sans didn't make it home until after midnight. He dropped his keys several times trying to make them fit into the front door. When he finally got the door unlocked, he pushed it open as quietly as he could. Papyrus had to be asleep already. Sans would get a metaphorical earful when Papyrus woke him up tomorrow morning, but that was then and this was now. Right now, Sans just wanted the world to stop spinning a little so he could sleep. Maybe for the rest of his life.

There was a light on in the kitchen, but the brightness made his eyesockets ache, so he ignored it and headed for the stairs, holding onto furniture as he went. He heard movement from the kitchen, but ignored that too. Probably just that small dog that kept getting into their house.

"Sans?"

"Shit." He kept going, bracing himself against the couch. "I'm fffine, bro, I'm just. Goin' to bed."

He heard his brother come to stand behind him, but Sans kept moving. The stairs would be tricky. He wondered if he could teleport in this condition. Probably best not to risk it. He could just take one stair at a time, or maybe he could just sleep on the staircase.

"You're four hours late."

"Uh huh."

"I was worried, Sans."

Sans stumbled and caught himself on the banister. Almost there.

"You're allwas worryin' 'bout me, Paps."

"Sans!"

Sans winced. "God. Don't shout."

"Are you-are you DRUNK? Are you actually DRUNK? Sans! You know better than this! You're usually so good at being CAREFUL!"

"Yeah." Sans tried for the first step and missed. He tried again. "Usually, heh."

"Have you been at Grillby's THIS WHOLE TIME? And you didn't even CALL?"

"Bro, I can't do this righ' now." He made it to the first step and tried the second one. "Got these, uh. These stairs t'…yanno, they're always upta somethin'. Heh. An' I can hear my bed callin' me. Got a hot date. Can't miss it. I'd be. _Re_ miss. Heh."

"SANS!"

"Shhhh."

"Sans, please! I can't BELIEVE how irresponsible you're being! How did you let yourself get this drunk? How did GRILLBY let you get this drunk? I was worried about you! Why didn't you call? After that-that TERRIBLE ACCIDENT with Snowball-"

Sans started laughing. Accident. _It was an accident. It was an accident._ Hilarious. That was utterly hilarious. He almost had to sit down on the stairs he was laughing so hard.

Papyrus didn't say a word until Sans's laughter had petered out and died. Sans leaned heavily on the banister and hiccupped, then tried for the next stair.

"Sans…what's…what's going on with you lately?"

"Nothin'."

"You're lying. Why do you do that? You always do that."

"Cause it's th' best position t'be in for sleepin'."

"STOP WITH THE PUNS AND BE SERIOUS FOR ONCE, SANS!"

"Sounds like too much work."

Sans was halfway up the stairs now. He tried for the next one, missed, and lost his footing. Papyrus caught him before he could fall very far and Sans ended up just sitting on one of the steps. He pressed one hand to his forehead and squeezed his eyesockets shut so he wouldn't have to look at his brother.

"Okay. Okay, fine."

He draped his other hand over his knees and hunched in on himself. Papyrus kept one hand on his shoulder, but Sans still couldn't look at him.

"Just. Just a long day, bro, that's all. Needed t'take the edge off. Got carried away. I can-I'll tell Grillz t'cut me off next time."

"It's not just today, brother." Papyrus crouched on the steps below him. "This has been going on for…for years now, I think. You've been…different. And it's been-I've been-concerned. I'm worried about you."

"You're _always_ worried." Sans gritted his teeth against his hand and pretended it was just a grin. "I'm not gonna-gonna miraculously gain more HP, bro. Not gonna wake up an' stop bein' lazy one day. Not gonna suddenly transform into a good person."

"That's NOT what I'm worried about and YOU KNOW IT! You KNOW this isn't about your HP or your laziness! What WORRIES me is that you never TELL me anything! Why can't you just TELL ME why you had such a bad day that you had to GO DRINKING FOR FOUR HOURS? What WORRIES me is-is you saying you're not a good person! How could you not be a good person, Sans? You're the brother of the GREAT PAPYRUS! That makes you ALMOST as great as me!"

Sans could feel the collapse coming. He crushed both hands against his face and sucked a breath through his teeth.

"Papyrus, I can't-I can't do this. I can't tell you cause there's nothin' to _tell._ Just stop, okay? Just stop. Please. I just wanna sleep. I'll be fine t'morrow. Won't do this again, I swear. I just wanna _sleep."_

Papyrus was silent for what felt like a long time. Longer than Papyrus should ever be silent for. Sans couldn't bear to look at him. Couldn't bear to see the disappointment and worry and confusion on Papyrus's face. He wanted to tell him, wanted to just collapse and let it all come spilling out, how another monster was dead, how he had thought he was going to die too, how he had practically hand-delivered a human child to King Asgore, how the Underground was now one soul away from breaking the barrier, one soul away from the end. One more dead child to come. How this had all happened before. How this all _kept happening._ How children died, people died, and somehow _Sans,_ Sans with 1 HP, Sans who wasn't even a good person, _kept surviving._ How it was all, all of it, just some horrible, cruel _joke._

He didn't say a word. Papyrus was waiting for something, for Sans to say something more, to finally give him a reason to love him at all, and Sans gave him nothing.

This was probably it. This was probably the moment he pushed Papyrus too far and Papyrus finally, at last, gave up on him. And good for him. Good for him. He deserved so much better.

"Fine."

Sans heard his brother rise.

"Alright, Sans."

Papyrus slipped his hands under Sans's arms and lifted him up off the staircase. Sans was forced to uncover his face and actually look at his brother. Papyrus looked…

Tired.

"What're you…?"

Papyrus gathered Sans into his arms. "You said you wanted to sleep. So! The Great Papyrus will carry you to your room. I don't think I trust you on the stairs right now."

"You don't…" Sans's head lolled against Papyrus's shoulder as his brother carried him up the rest of the stairs. "You don't hafta do this. Y'know, you. You could make me go sleep at the inn, or somethin.' You don't hafta…"

"Yes, I do."

 _"Why?"_

"Because you're my brother, and I love you. No matter what."

Like it was that simple.

Sans gripped Papyrus's shirt, wrinkling it. Papyrus opened the door to Sans's room and sighed at the mess like he always did.

"Yer so cool, bro."

"I know I am."

"Love you, too."

"I know you do."

Papyrus deposited Sans on his bed. Sans let himself tip over and curled up on his side.

"Are you even going to undress yourself?"

"Nah."

"Well, I draw the line at helping you with that."

"Heh."

"Try to at least not sleep with your slippers on, alright? They're filthy."

"Yea."

"Get some sleep, Sans." Papyrus hesitated. "Tomorrow…will be better, right?"

"Yeah. Tomorrow."

Papyrus left. Sans waited until he was sure his brother was out of earshot to break down. Papyrus did the same.


	12. Falling

.

 **ENTROPY**

* * *

Chapter 12: Falling

Warnings: Chapter contains mentions of **animal mortality** and **references to parental neglect** and **emotional abuse.**

 _If only I could make a monster's soul last...  
_

* * *

In the space of two months, three of the dogs of Snowdin had Fallen Down. Doggerel was the first. Everyone had known it was coming. His health had gone rapidly downhill after his retirement, until finally he simply didn't get up one morning. Dogaressa had found him comatose in his bed. She and her husband had taken turns sitting beside him, doing all the usual things one did when a monster had Fallen Down-keep him comfortable, tell him how much they loved him, tell him to hang on, and wait to see if he miraculously got up one more time. It could happen, but it was very rare. Falling Down was almost always the beginning of the end.

Doggerel didn't get up. But he also didn't go to dust right away. That wasn't particularly uncommon. Some monsters lingered for months after Falling Down, and Doggerel had always been tenacious.

A month later Doggerel was still hanging on, and in the meantime Best Dog had Fallen Down as well. It had been sudden; a passerby had found her immobile at her sentry station. According to Greater Dog, she'd been perfectly fine that morning. She'd simply taken a turn.

A week later it was Doggo Sr. He'd said that he'd been feeling off for awhile, and then one night he'd collapsed at Grillby's. Lesser Dog helped Doggo Jr. carry him back home. Doggo said later that he'd seen his father stir later that night, but Doggo Sr. never got up. None of them did.

It wasn't unheard of for monsters to Fall Down in small clusters like this. One Fall sometimes set off a chain reaction, particularly in tight knit communities. All of Snowdin came together in support of the dogs, Sans and Papyrus included. Sans left most of the comforting and sympathy to Papyrus, as he was better at that sort of thing than Sans was. Sans just helped with the organizational stuff-making sure sentry shifts were covered, helping with funeral arrangements and buying dog food for the surviving family. As well as drinks from Grillby's, for when things got particularly stressful.

There wasn't much else that could be done other than wait for the Fallen to either get up or go to dust. It could be days or weeks. Sans kept himself occupied and tried not to think too hard about any of it. He couldn't mourn them while they were still technically alive, while they could still possibly get back on their feet. It wouldn't happen-Sans just wasn't that optimistic-but treating them like they were already dead felt like the nail in the proverbial coffin. Sometimes all it took was for someone who loved you to hope enough, to not give up on you enough, and then you could drag yourself up out of the abyss for awhile longer. Sometimes. Papyrus certainly thought so.

Sans, though, wasn't thinking about it. He sold hotdogs, picked up extra shifts, practiced magic, calibrated puzzles and patrolled the more remote areas of Snowdin. It was nice to get away. Being in the same room as a lot of quiet, distressed people made him feel weird.

He had finally started exploring the section of forest beyond his sentry station. The trail back there was poorly kept and overgrown. Not even the teenagers came out this far, as there was nothing interesting except more trees and a small, broken bridge over a chasm. Said chasm was too wide to jump over, or for a Snowdrake to glide over. No one lived past the chasm anyway, so no one had ever bothered to fix the bridge-though it was on Papyrus's "Features to Improve with the Tactical Employment of Puzzles" list, which was a real list.

Sans had never been past the chasm either, but today had been somewhat nerve-wracking. Best Dog, ever a fighter, had stirred just slightly, which had set Greater and Lesser Dog both to howling. It was false hope, which was even worse than regular hope, so Sans had excused himself.

He came to the chasm and decayed bridge and studied them both for a moment. He had a clear view of the other side, and there didn't seem to be any hazards he might land on, so he just shrugged and teleported across. There was only the barest hint of a trail on the opposite side, mostly obscured by snow, and the woods were very thick here. If the humans had come from beyond here, as Sans had always assumed, how were they getting across? There didn't seem to be an easy way to climb down and then back up. Maybe there was a fallen tree somewhere that acted as a natural bridge; or maybe humans could simply jump that far. At this point, he wouldn't put it past them.

He checked his phone to make sure he still had reception, then continued into the forest. The trees grew closer together the further he walked, shutting out most of Snowdin's dim ambient light. The path was virtually nonexistent, and Sans had to teleport himself past some fallen trees and snow drifts. It was completely silent; it was nice. Sans enjoyed the quiet.

Not far past the chasm the path and forest stopped abruptly. Well, that explained why no one lived out here-there was a sheer cliff wall that looked like it cut through the entire forest. Sans looked up. The rock wall disappeared into the darkness. Perhaps it went all the way to the ceiling. It was almost like he had found the edge of the Underground itself, but that couldn't be true. The Ruins should still be out here somewhere, presumably beyond the wall. Sans walked closer so he could examine the stone. The wall was overgrown with vines and moss, though in places the moss looked almost indented. As Sans laid a hand against the stone, he realized why. There was a distinct, rectangular shape in the wall, exactly like a door.

"Huh," he said aloud. "How about that."

This had to be the entrance to the Ruins. It looked like it had been opened relatively recently. Last year, probably, when the sixth human had come through. Another thing he wasn't thinking about.

Sans felt around the edges of the door. There were no hinges that he could find, nor was there a knob or a handle. It didn't even look like it could be opened from this side at all. He wondered if anyone was living inside. He'd always heard that there was a whole spider clan that lived in the Ruins. They'd been separated from the main clan some years ago, and Muffet, the weird monster who ran the spider bakery, had been trying to reunite them ever since. At least that was the claim she always made whenever people asked about her exorbitant prices.

Spiders wouldn't be able to open a door like this, though. The humans must have just been opening it themselves. Though it was kind of odd that they bothered to close it behind them.

Ah, well. Again-wasn't thinking about it. On a whim, Sans raised a fist and knocked on the door. It made a hollow sound. A nice echo.

He waited a minute. No one answered, not that he had really expected anyone to. He shrugged and tilted his head as an idea came to him. Then he knocked again, two rhythmic knocks.

"Who's there?" he said, grin widening. "Figs. Figs who? Figs the doorbell, it's broken."

That was terrible. He snorted and knocked again.

"Who's there? Mikey. Mikey who? Mikey doesn't fit in the keyhole."

He chuckled. He'd always thought it was important to laugh at your own jokes, especially if no one else was. He knocked again.

"Who's there? Canoe. Canoe who? Canoe open this door? It's cold out here."

He could get used to this. The door and the empty woods made a pretty good, impassive audience. No one came out here, no one lived near here, and very few people even knew this place existed. It was the perfect place to get away for awhile, get some peace and quiet. He'd been running out of such places lately, as he had already explored most of the rest of the woods. He could practice knock knock jokes and magic at the same time and no one would bother him.

Perfect.

The distraction lasted a few hours-he even managed to top it off with a quick nap against the door-until his phone rang. It was Papyrus.

"Sans, where are you?"

"In the woods near my station. I found a cool door. What's up?"

"You had better come back into town, brother. I'm-afraid there's been another Fall."

Sans scrubbed at his face with his free hand.

"Aw, jeez. Who is it this time?"

"Mrs. Drake. Mr. Drake has gone out looking for their son, Snowy, so some sentries have offered to look after her while he's out! Your presence would be QUITE helpful!"

Sans stifled a sigh. Back to the depressing grind, it seemed.

"Alright, bro, I'm on my way. I'll take a shortcut."

"Thank you, Sans! Boy, I-really, really hope no one else Falls Down! It's getting! Quite harrowing around here! I hope they all wake up soon!

"Harrowing" was almost putting it mildly. Papyrus had not taken the recent events well at all. Sans was never actually all that sure if Papyrus…fully understood the concept of death. Or rather, it wasn't so much that he didn't understand death-Papyrus wasn't naive. He just had a very, very hard time accepting it. Sans thought it was some kind of denial, but he had never done much to discourage it. It had honestly just not come up that often. And once upon a time, that denial had saved his own life.

"Yeah. Let's hope so, huh? See you soon."

Sans pocketed his phone and headed back. He landed at home first to drop a few things off, then steeled himself and teleported to the Drake house. He paused at the front door, wondering if maybe he should bring some kind of gift, even just a bag of birdseed. He didn't know the Drakes all that well. Mr. Drake was a regular stand-up comic at the MTT Resort, but the guy wasn't a fan of puns and therefore wasn't a fan of Sans, either. Mrs. Drake had always been a fixture around town, the sort of monster who liked handing out treats to children. All Sans really knew about her was that she had been frail for most of her life.

Should have talked to her more. They had something in common, after all. Too late now.

Sans knocked on the door. One of the ice slimes from the neighborhood answered a few moments later.

"Goodness, that was fast. Didn't your brother just call you a few minutes ago?"

Sans put on a faint grin. "I know a shortcut."

"Well, come in, come in." The slime monster wriggled backward to allow Sans. "I appreciate this. I know Mr. Drake does as well. Foxtrot is also here."

"When did it happen?" Sans asked, stepping inside.

"An hour ago." The slime monster lowered their voice once the door was closed. "There's been no change since."

 _Figures,_ Sans thought, but he kept it to himself.

The house was quiet. Foxtrot, a fox monster who lived in town and had a sentry station in Waterfall, was sitting at the kitchen counter nursing a mug of coffee. He raised a paw in silent greeting. Sans did the same.

"Where's Papyrus?"

"Sitting with Mrs. Drake," the slime monster said. "Now that you're here, I think I will take my leave. I need to get home to my own family."

"Yeah, of course. We got this covered."

The ice slime sighed and gave a sullen wiggle.

"Nothing but bad news lately, eh? Feels like the world's coming to an end."

"Well…" Sans started to think of a good pun, but stopped himself. Foxtrot and the slime would probably just find it insensitive. "…Heh. I guess I know what you mean."

The slime left. Foxtrot got up long enough to hand Sans a mug of lukewarm coffee. Sans just nodded his thanks. The fox monster was a quiet sort, especially when upset.

Sans found his way to the bedroom. The door was partway open and Papyrus was sitting in an armchair next to the bed, reading softly aloud from a book. Fluffy Bunny, of course. Sans paused in the doorway, glancing only once at Mrs. Drake. He found it hard to look at the monsters who had Fallen Down. They all looked the same-pale, motionless, scarcely even breathing. They always looked like some kind of strange painting of a person, rather than a person themselves.

He wondered if he had looked like that.

Sans dismissed the thought as soon as it had formed. None of this was about him.

"Hey, bro." He stepped into the room. Papyrus stopped mid-sentence and looked up, grinning when he spotted Sans.

"Brother! Thank you for coming! I was just reading my favorite book to Mrs. Drake! If she can hear it, I am certain that she will become a die-hard Fluffy Bunny fan when she wakes up!"

"Heh, the Fluffy Bunny fandom's gaining so many new members."

Papyrus had been reading Fluffy Bunny repeatedly to everyone who had Fallen Down. The dogs all seemed to appreciate it. Doggo had commented that every dog liked to dream about chasing rabbits, and that Papyrus couldn't have picked a better book for sleeping dogs.

"Don't be a weird nerd, Sans."

"Way too late for that, bro." Sans leaned against the wall, trying not to look at Mrs. Drake. "Where, uh, where did you say Mr. Drake was?"

"Out looking for their son, Snowy." Papyrus closed the book, keeping a finger between the pages. "I guess he's been spending more time in the woods lately?"

"He's a teenager now. They do that."

Papyrus sniffed primly. "I certainly never ran off into the woods when I was a teenager!"

"No, _you_ would run off into Waterfall looking for humans," Sans said with a wry grin.

Papyrus cleared his nonexistent throat. "Never mind all that. I just hope she's not too worried about Snowy."

"I'm sure he's fine."

"Of course! But, parents worry. Don't they?"

"I, uh, I guess."

Papyrus hid a yawn. "Raising children sounds like it is very difficult!"

"Yeah. Probably." This was not a topic Sans wanted to talk about right now, or ever.

"Perhaps even a challenge worthy of the Great Papyrus!"

He had to laugh at that, at least. "Heh. Yeah, you'd make an amazing parent, bro."

"Of course I would!" Papyrus beamed. "Imagine a bunch of little Papyrus-es running around!"

"Jeez. That might be too much coolness for the Underground. The whole place might _freeze."_

"Ugggh, Sans. That's terrible." Papyrus paused, tapping a finger against the cover of his book. "Do you ever think about having kids, Sans?"

"Nope."

"So abrupt! Why not?"

There were a lot of answers Sans could give. For one thing, having kids implied that there was anyone in the world who wanted to have them _with Sans,_ which he was pretty sure was a scientific impossibility. There was also the fact that Sans could barely be trusted to look after himself-looking after an actual child was out of the question. Given his track record, he probably shouldn't be trusted around kids at all. On top of all that, Sans knew-with the same certainty that he knew he loved his brother-that he wouldn't make it to fifty. It was enough of a miracle that he'd made it to his thirties. Bring a kid into the world, and then potentially leave them alone before they had a chance to grow up? That was too cruel.

"Ehh." Sans gave a languid shrug. "I'd make a terrible parent."

That summed things up pretty succinctly.

"You'd make a fine parent! You pretty much raised _me…"_

Sans shifted against the wall. Papyrus tested this boundary once every few years or so. They were probably overdue for another attempt. That didn't exactly make Sans appreciate it any more. Sans had to give Papyrus credit, though, because this was the perfect time to try. It was very clever. Even Sans would have a hard time bad-mouthing parents while a parent was lying half dead in the room.

But, no, that was wrong. Papyrus wasn't manipulative, not like Sans. He could be sneaky, but never manipulative. Sans couldn't think of it that way. With all the monsters Falling Down lately, Papyrus had been more contemplative than usual. He had to be thinking about this sort of thing a lot. Mortality, illness, family. Parents.

"Guess it's pretty amazing you turned out as well as you did, huh?"

"Sans…"

"Papyrus, you…" Sans kept his voice gentle and rubbed the back of his skull. "You can ask if you want, but the answer's gonna be the same as always."

"I wasn't going to ask anything." There was just the slightest hint of sulkiness in his tone.

Sans folded his arms and sighed, closing his eyesockets.

"Some people just aren't meant to be parents. You know?"

Some monsters just weren't good at it. Judging by all the human children who had ended up in the Underground over the years, Sans had to believe that some humans weren't, either.

Papyrus was frowning, staring at the edge of Mrs. Drake's bed.

"I suppose that I just…still do not understand it. Even after all these years."

"That's alright, bro. I don't, either. I don't think we're supposed to." He chanced a look at Mrs. Drake's form. She looked almost like she could be asleep. "We're supposed to understand the good ones, like her. Most of them _are_ good."

"But I'm-I'm sure they _must have_ been-perhaps they just didn't try hard enough? Anyone can be a good person if they just try!"

He always did this. Never had an unkind word to say about anyone, no matter what they had done. He always tried to find the good in everyone.

Sans made himself smile.

"Yeah. Maybe you're right, bro."

Papyrus was so cool. Sans honestly envied him sometimes. Being able to just forgive and forget like that must be nice. Sans just…couldn't do it. He had tried. He wasn't much for grudges, but some things just seemed unforgivable. It would probably feel a lot better if he could just get over it and forgive Gaster for the terrible things he had done.

It would probably feel better if he could forgive their parents as well.

Papyrus's grip tightened on his book.

"Then…why didn't they?"

He hated this part. The confusion, the disbelief in his brother's voice; the way he frowned at nothing. The sheer inability to comprehend. Sans never had an answer. After twenty-some years, the answer was still the same.

"I don't know, Papyrus."

His brother fell silent, still staring at nothing and gripping his book too tight. Sans watched him carefully.

"Bro, are…are you…?"

"Well!" Papyrus sat up straight all at once. "This is no time to be selfishly thinking of myself! The Great Papyrus has a duty-and that duty is to keep an eyesocket on Mrs. Drake and be sure that she stays comfortable! Until Mr. Drake returns and until she wakes up! Positivity is the key. The Great Papyrus will not be defeated by unpleasant thoughts!"

He thumped a fist against his sternum to accentuate the point. Sans chuckled a bit. That was that. Papyrus probably wouldn't bring it up again for another year or so. Not until something else reminded him.

"That's the spirit, bro." He watched as Papyrus stifled another yawn. "You wanna take a quick break, though, get coffee? I can watch her."

Papyrus gave a vigorous shake of his head.

"Before I've finished the story? Never! The Great Papyrus never takes breaks!"

"Pfft, that's just plain untrue."

Papyrus grumbled a bit. "The Great Papyrus very, very rarely takes breaks!"

"There ya go. No breaks at all is unhealthy, anyway."

Papyrus shot him a look. "No more unhealthy than too many breaks, _brother."_

Sans put on his most shit-eating grin and held out his half-finished mug of coffee. Papyrus gave the mug and Sans a dubious look, but accepted. Sans took a seat on the floor. Hopefully Mr. Drake would find Snowy and return quickly. Papyrus needed sleep, perhaps even more than Sans did, which was saying something. This past month had run his brother ragged.

"Did you mention on the phone that you'd found a door?"

"Oh, yeah." He'd almost forgotten. "This big stone door, real deep in the woods. Past that small crevice near my station."

"Ah! With the broken bridge! I keep meaning to fix it… Where does the door lead to?"

"Probably the Ruins." Sans shrugged. "I can show you tomorrow. It's cool. Great for knock-knock jokes."

"You find the door to the Ruins and you decide the _best_ use of your time is knock-knock jokes?" Papyrus sipped his coffee with the most judgmental sideways glance Sans had seen from him in a good while. Sans laughed.

"What can I say? I'm _humerus_ like that."

"I wish I could say I was surprised!"

Now it was Sans's turn to yawn. Papyrus held the mug out to him, but Sans waved it away. Papyrus needed it more than he did, and if Mr. Drake was going to take awhile, then Sans wouldn't mind a nap. Even if it meant sleeping in the same room as someone who was Fallen Down.

Papyrus flipped open his book again and continued from where he had left off. Sans hoped that Mrs. Drake could hear it. Fluffy Bunny always got a happy ending. They could all use some more of those lately.

* * *

He was in a bedroom. A child's bedroom, the walls painted a calm shade of blue, the floor plain wood and dotted with colorful rugs. There were a few pictures and posters on the wall, most notably a copy of the periodic table that had clearly been torn out of a textbook. There was also a poster of the Earth as seen from space. There was a small, child-sized desk in the corner, from which a small lava lamp lit the room. Everything about the room seemed very comfortable. Very homey.

Everything except the bed.

Sans stood in a corner of the room, hands in his pockets, watching as static crawled along the bed cover. The headboard was a mess of holographic glitches. There was a too-small lump in the middle of the bed, covered by television snow.

Kneeling at the side of the bed was a very young skeleton. He was the only thing untouched by the static. Wearing a green and orange striped shirt, small head resting on folded arms as he struggled to stay awake. Struggled to keep his eyesockets on the lump of static.

"You know," Sans said aloud, because the small skeleton by the bed wouldn't hear him. "I could have gone the rest of my life without you ever knowing about this. That woulda been fine."

It was dark in the room aside from the lava lamp, and the shadows on the ceiling writhed.

"I DID NOT CREATE THIS."

"No, I kinda figured. You wouldn't have _known_ about this. No one does. No one's supposed to."

"MY APOLOGIES."

"Don't apologize when you're not actually sorry, Doc." Sans shook his head. "…Gaster. Your name, uh, takes an extra second these days."

"I NEEDED TO SPEAK TO YOU."

The skeleton at the edge of the bed shifted, and Sans went very quiet and very still. It was just a dream, he knew it was, but he-he wasn't supposed to be here. _Gaster_ wasn't supposed to be here. This was something that Sans never looked at, never examined, never thought about if he could help it. This was an intrusion. This shouldn't have been disturbed.

The young skeleton rested his forehead on his arms and gave a muffled groan.

"Come on, stay awake! Gotta stay awake! Gotta be zere when he wakes up."

Sans hissed through his teeth. God, that voice. He sounded so young.

"Can we take this elsewhere? Just-take over the dream, make it something terrible, like you usually do. I don't want to see this."

"IT DOES NOT WORK LIKE THAT." Gaster paused thoughtfully. "WHAT IS THIS?"

"Something _private."_ The words came out sharper than Sans had intended. "If I know I'm dreaming, doesn't that make this a lucid dream? Doesn't that mean I can change it?"

He gave it a try, making himself think of something else-anything else. The door in the forest, knock-knock jokes. Math equations. Grillby's. The old lab, the Core, _anything._

Anything but this.

The world shuddered and then snapped back into place, the shadows twisting on the ceiling, glitches racing through the bed, because what was _lying there_ might as well have been a glitch. A mistake. Something _broken._

"Gotta stay awake," the skeleton by the bed chanted, bouncing in place. "Gotta stay awake. Gotta stay awake!"

The skeleton reached out and patted the lump in the bed very gently.

"Come on, Sans! If I gotta stay awake, zen, zen zat means YOU gotta wake up too, okay?"

He'd been, what, four at the time? Papyrus had been loud even back then. Sans pushed his hands deeper into his pockets.

"I DO NOT UNDERSTAND."

"It doesn't matter." Sans shrugged. "It's just a dream, anyway. Just tell me what you came here for. Must be important if you're waltzing into my dreams this time. I'd, uh. I'd rather get this over with. Cause I'm-"

A light came on out in the hallway and Sans heard footsteps approaching. Young Papyrus heard it too, lifting his head from the mattress and looking toward the door. Sans gritted his teeth, bracing himself. This was fine. It was fine. Just one more thing he had no control over. One more weapon Gaster had against him, for when Gaster decided to go back to the good old days of trying to break Sans's mind.

Gaster was silent. The bedroom door opened.

A tall skeleton walked in. Their head was completely obscured by static.

"You're in here again?" The skeleton heaved an exhausted sigh. The voice was female and tired, her words tipped with brusque serifs.

She raised a hand to rub at her forehead.

"Papyrus, you cannot keep doing this. It's three in the morning. I heard you yelling from down the hall. Must you _always_ be so loud? Go back to your room and go to sleep."

"But I wanna be here when Sans wakes up!"

The skeleton put her hands on her hips.

"We've been through this, dear. He's not going to wake up." To her credit, her voice was gentle; but the gentleness couldn't quite do away with the exasperation. "Monsters who have Fallen Down do not get up again. He was always fragile. This is just how things are. I explained this days ago."

"Mrs. Handy said her friend's papa, um, Fell Down one time and, and zen he woke up. And, and Punchy down za street, zey said zat um, one time-"

"It is very rare. It almost never happens, and when it does, it happens to very strong monsters who are determined to survive. Sans was never strong. Listen, dear, I know it's hard to accept. I know it's sad. I know you miss him. But there is nothing that you or I or anyone can do now."

Papyrus shook his head vigorously, his little face screwing up into the most stubborn expression he could muster.

"No! He's my bruzzer." His chin wobbled, but he didn't cry. "I d-don't want him to go."

The static around her head flared, buzzing loudly, almost overtaking the rest of her body. She was angry. Tired and angry.

"He's already _gone,_ Papyrus. Denying it like this is just going to make it harder. You're already making it harder on me and your father. Is that what you want? Are you just going to stay by his bed for the rest of your life? You have to give up sometime."

Papyrus turned his back on her, bracing his hands firmly on his knees, fixing his eyesockets on the lump in the bed once more.

"Never," he said, with more resolve than a four-year-old should be capable of, with more resolve than the lump in the bed really deserved. "I'll _never_ give up."

There was a long pause. The woman folded her arms, apparently staring at Papyrus's back. Sans pressed into the corner, wishing he could shrink down into nothing, fall out of time and space and everything else. Gaster remained uncharacteristically silent as the scene unfolded.

"Fine," their mother said at last. "Fine. Do whatever you want. I don't care."

With that, she turned and left, closing the door hard behind her. Her footsteps faded into nothing and the hallway light switched off.

Papyrus sniffled.

The room started to fade slowly away, blurring at the edges. Papyrus was the only thing that remained in focus. Sans watched his little brother cry at his own bedside, completely alone.

The silence stretched on. Sans pulled his hands out of his pockets and folded his arms across his chest instead, trying not to look like he was hugging himself.

"I. DID NOT KNOW."

"Because I don't talk about this." Sans's voice was soft. The landscape shifted into a long dark hallway, Papyrus in the distance. Skeletons appeared in the darkness, crouched on the floor, covering their faces with their hands. They all looked the same, and at the same time, completely indefinable. "I never talk about this. It was a million years ago. Ancient history. Doesn't matter anymore."

Gaster was quiet for awhile, long enough that Sans let himself hope that maybe Gaster would drop the subject. For once.

"IF YOU ARE DREAMING ABOUT IT. THEN IT DOES STILL MATTER."

This was why Sans never put much stock in hoping. He pushed off from the wall and started walking down the hallway toward his brother, trying to navigate around the crouched skeletons. Some of them were whispering. He tried to ignore them.

"You my therapist now?" Sans sighed. "There've been some Falls in Snowdin. Guess it just reminded me."

The world was completely black now, but Papyrus was still there out in the darkness, illuminated, as if he were a source of light. Sans could still hear him crying. He wished he could block out the noise. He had to reach him. Had to get to him and tell him that it would all be okay, it would be fine, that he would wake up the following morning, would be back on his feet only a few days later. That Papyrus could sleep, should just let himself sleep, because for once everything really would be okay in the morning.

He just had to get past these other skeletons first. They were whispering so loudly. It was just a dream. It was just a dream, he was walking down a dream hallway with Gaster behind him. None of it was real.

"You…you know that theory about how people can still hear sometimes when they're Fallen Down? It's true." He tipped his head forward, toward Papyrus's far-away form. "I only came back cause I heard him."

"IS THAT. THE REASON FOR YOUR HP?"

"No. I've always had just one. I was born like that. Came out wrong." Sans's grin widened and widened. "Imagine the disappointment."

 _"Such a disappointment,"_ one of the skeletons murmured.

Gaster was quiet again. Sans could sense him, or rather the absence that was him, shifting its way through the darkness behind him.

"YOUR PARENTS-"

"Don't. Please."

"I AM TRYING TO. UNDERSTAND."

"There's nothing to understand. You had no right to come into a dream like this, and you have no right to ask. I don't owe you anything." Sans forced himself to breathe evenly, forced his hands to uncurl in his pockets. It was fine. It was just a dream. Just a scrambled up memory. The skeletons whispering to him weren't even real.

"Some people just aren't meant to be parents. That's all. Anyway. You said you needed to talk to me. So, talk. You'd better-you'd better make it fast. I think I'm having a nightmare."

"IS IT. ALWAYS LIKE THIS. FOR YOU?"

"Of course not." Sans stumbled as he tried to step around two skeletons. "If it was like this all the time I'd never get any sleep at all."

Papyrus was still in the distance. It didn't look like he was getting any closer. The whispers were starting to drown out the crying.

 _"A mistake."_

 _"A wonder he lived as long as he did."_

"I said make it fast, Gaster."

It felt like Gaster was confused, bewildered by the dream. It took him a moment to respond.

"THE DOOR."

"To the Ruins, right?"

"WATCH THE DOOR."

"If it's where the humans have been coming from, then-"

One of the skeletons stood up. Sans flinched away, but the skeleton didn't move further. It didn't even uncover its face.

 _"I'm so sorry. We've never seen a case like this."_

Another skeleton stood up on Sans's opposite side.

 _"It is likely that he won't make it out of infancy. I am so sorry."_

A third, this one ahead of him.

 _"There are some experimental treatments we can try."_

Bones were creaking behind him. Sans didn't bother to look. More of them had to be standing up now. He walked faster.

"SANS."

"Just keep talking. Don't be cryptic, please, just this once."

"IT IS DIFFICULT TO PARSE. THE WORDS. THE CONCEPTS. SPACE AND TIME DO NOT. MEAN THE SAME THINGS TO ME. AS THEY ONCE DID."

"Okay, I get that. I get that, I do." Another skeleton stood up, and Sans was still miles and miles from Papyrus. "But do the best you can, because we're both running out of time. And your being here isn't helping the, uh, nightmarish…qualities."

They were all standing up now, unfolding from the floor like flowers.

"WHAT IS COMING IS NOT HUMAN. IT IS AN ANOMALY."

"This isn't anything new, Gaster, come on."

 _"You know we can't let you go out."_

 _"It's too dangerous."_

 _"You could get hurt, and then where would you be?"_

 _"What would people think if we let something happen to you?"_

It wasn't real. He just had to keep telling himself that it wasn't real. It was just a stupid dream. He hadn't had a nightmare about this subject in literal decades, but it didn't matter. It was still just a dream.

"CHECK YOUR REPORTS."

"My…what?" Sans almost paused, but one of the skeletons reached for him slowly. He sped up. "You-you mean from the scanner I built? I never finished it."

"FINISH IT."

"It needs to be-" Another skeleton reached for him, phalanges catching his sleeve for just a moment. He stifled the sound that threatened to escape him and kept going.

"It n-needs to be calibrated. I need an engineer, and Alphys doesn't-she doesn't-we haven't spoken in over a year."

"SHE CAN HELP YOU."

 _"Why couldn't you just have been normal?"_

"YOU NEED TO SEE IT FOR YOURSELF."

Sans couldn't hear Papyrus at all anymore. He was just a speck of light, far away in the darkness. Hands grasped at him. This time, one of them caught on and held.

"Talk to Alphys, finish the scanner, check the reports, okay." More grabbed on, clutching at fabric or bones. "It's just a dream. Gaster, can't-can't you just-?"

"NOT HERE. NOT WITHOUT HURTING YOU."

It was just a dream. The skeletons uncovered their faces entirely. Their heads were obscured with static. It was just a dream.

"Then I want to wake up now."

"SANS. FOCUS. IT IS A DREAM."

 _"Why weren't you watching your brother?"_

 _"You were supposed to be watching him."_

 _"You're useless."_

Papyrus disappeared in the dark. His crying stopped.

"SANS. TRY TO FOCUS. THERE IS MORE YOU MUST KNOW."

"I can't- I can't-"

"THERE IS SOMETHING ELSE. SOMETHING I HAVE. NOT BEEN ABLE TO SEE CLEARLY. SMALL. OVERLOOKED. SANS. YOU MUST TRY TO FOCUS."

They were surrounding him now, holding him tight, not letting go. The whispering drowned out everything else.

 _"You're embarrassing us."_

 _"He probably won't make it to five."_

 _"He probably won't make it to ten."_

 _"It is unlikely he will make it to adulthood."_

 _"I'm so sorry. I wish there was more we could do."_

 _"Not now. I'm tired."_

 _"Stop bothering me."_

 _"And this is the thanks we get?"_

 _"He'll never have a normal life."_

 _"He came out wrong."_

 _"You came out wrong."_

 _"It's because you came out wrong."_

Sans clapped his hands over his skull.

Something shook him. The dream wisped away like smoke and Sans came awake with a short, sharp gasp. He blinked, trying to look around. He didn't recognize this room. Where was he?

Someone was gripping his shoulder. They gave him a small shake.

"Sans? Oh-you're awake."

Papyrus.

Sans blinked again. "Wh…?"

"Were you having a nightmare? You looked very tense." Papyrus let go, but he was watching Sans with a concerned expression. Sans stared blearily around the room, trying to figure out where he was. It wasn't his bedroom. There was a bed nearby with a sleeping figure in it.

Oh. Oh, right.

Sans sat up and stretched, popping his joints. Papyrus made a face. There were other voices from the direction of the kitchen, one of which sounded an awful lot like Mr. Drake.

"Sorry, didn't mean to fall asleep."

"Hmph. I highly doubt that."

"Heh. What time is it?"

"Almost midnight. Mr. Drake just got back, and Snowy is safe and sound. Only, the two of them seem to be…maybe fighting? So I think it is perhaps time we left. Are you alright?"

"Me, yeah."

"You're covered in sweat."

"Oh." Sans dragged the back of his hand across his forehead. It came away damp. "Nah, I just went swimming in my dream."

Papyrus gave him a look that Sans had become very familiar with these last few years. He then stifled a sigh and stood up from his chair.

"Let's go home. Mrs. Drake is in safe hands now! Or-safe wings, at least."

Sand dragged himself to his feet, spine giving a satisfying crackle. He followed Papyrus out of the room, casting a parting look in Mrs. Drake's direction. She wouldn't get up, but…it would be nice if she could hear her family telling her they loved her. Though it sounded like Papyrus had been right-Mr. Drake and Snowy weren't quite yelling, but their voices were raised.

"-and ignoring mah calls like you always do-"

"-because you're always nagging me!"

"-and when your mothah is in this state-"

"-stop yelling and let me go see her!"

Sans tuned them out as he and Papyrus stepped into the kitchen. He'd had enough of family tension for one night, and he had other things to think about. The scanner in his basement lab, the old machine. Alphys. The anomaly that Gaster kept mentioning had to be coming soon; and from the implication, it seemed that maybe it was affecting the timeline. He'd built the scanner awhile ago to track changes in spacetime, the theory being that if he could find the rips and tears, maybe he could start to fix them. Without Alphys, he'd never been able to finish calibrating it. The thing worked, it just didn't actually _do_ anything yet.

Talking to Alphys was going to be…difficult.

"Sorry ya had to hear that." Mr. Drake was grumbling, as Snowy skirted past the skeletons toward his mother's room. "That boy, he's got no sense."

"Anyway! Now that the whole family is home! Sans and I figured that we would give you your privacy!" Papyrus's voice was a bit strained, though it was almost impossible to hear if you didn't know what to listen for. Family members fighting amongst themselves made Papyrus uneasy.

"Thank ya for watching her," Mr. Drake said, nodding. "Really means a lot to us."

"Of course! Any time! If you need anything else, don't hesitate to ask!"

"And, uh, you have our condolences."

Mr. Drake's feathers drooped a little. "Yeah…yeah. Again, thank ya. You boys better get on home. It's startin' ta snow."

The brothers left. Sans pulled his hood up against the snow, trailing behind Papyrus and stepping into his footprints. It didn't actually snow all that much in Snowdin, as weather was virtually nonexistent underground, but it was a pain in the coccyx when it did. Fresh, powder snow was harder to walk in than packed snow.

Sans focused on walking and on thinking about how best to talk to Alphys and how best to complete the scanner. If he kept his mind occupied, then he wouldn't have to think about the dream at all. Papyrus walked ahead of him in silence. Papyrus being silent at all was starting to become alarmingly commonplace.

"You, uh, thought about what book you want for your bedtime story tonight?"

Papyrus glanced back at him. He was smiling, at least, though it still looked a bit taut.

"Even though it's so late? You're usually FAST asleep by now, brother! In fact, I think it's the ONLY time you're ever fast!"

"Pssh. I can stay up long enough for a bedtime story. You know I'm always good for 'em."

"Well…since I already read _Fluffy Bunny,_ how about _Goodnight Moon_ tonight instead! We can pretend we're on the Surface too, saying goodnight to all the Surface things with the bunny monster protagonist! Just like old times!"

"Heh, classic. Great choice, bro."

"Of course it's a great choice! The Great Papyrus always makes VERY GREAT choices!"

"I dunno. The choice to add pinecones to the spaghetti the other night might've been juuuuust slightly less than very great."

"IT IS CALLED CULINARY EXPERIMENTATION, SANS!" Papyrus huffed. "You're a nerd who likes science stuff, you should understand about experimentation!"

"Heh."

Papyrus looked back at him again and paused, seeming to notice just how far behind Sans was lagging.

"Keep up, Sans! You said you weren't too tired for a bedtime story!"

"Sorry, bro." Sans missed the next footprint slightly and got snow in his shoe. "It's just all this snow. It's almost stoppin' me _cold,_ heh."

"Ugh, Sans. If you're going to be slow _and_ tell horrible puns, then I shall simply have to carry you!"

Sans waved a hand. "Nah, it's just a few more blocks. I can make it."

"Then the Great Papyrus will shuffle his feet and make a path for you! It will be like skiing without skis!"

"Pfft, can you imagine if-"

Sans overextended and one foot slid out from under him. He fell forward into the snow, managing to get his hands out before he could completely faceplant.

"-oof."

"Sans!"

Sans started chuckling as he pushed himself back up into a crouch, dusting snow off his sleeves.

"Oh, man. I think that was my best yet. He's beauty, he's grace, he's fallen on his-"

There was a crunch of snow, and in the next moment Papyrus was on his knees before him. Sans cut himself off as he saw the look on his brother's face.

Papyrus wordlessly wrapped both arms around him. He was shaking.

"Uh…Papyrus?"

"Don't…just don't scare me like that."

Oh. _Oh._

"Hey." Sans patted Papyrus on the back. "Hey, big guy, it's okay, I'm okay. Heh, come on, it's not a big deal. I just slipped in the snow, that's all. It was just the snow."

"I know." Papyrus's voice was muffled against Sans's shoulder. "I know. I overreacted. It-it is unbecoming for the Great Papyrus to overreact like this."

God, Sans wasn't sure he could take this, not after sitting with Mrs. Drake for so long. Not after that dream.

"It's okay, bro."

"I just…don't want you to…"

"I'm not going to."

"I keep thinking about it, Sans."

"I'm perfectly fine."

"Best Dog was perfectly fine." Papyrus's voice was ragged. Sans hadn't heard him sound like this in a very, very long time. "Mrs. Drake was perfectly fine. _You_ were perfectly fine, before you-"

"It's not going to happen. Come on, Paps, it's not gonna happen." Sans didn't know how to do this. Papyrus hadn't needed comforting in so long. He was always so upbeat, and even though he tended to let his guard down around Sans, it was almost never this bad.

The Falls must have gotten to Papyrus more than he'd been letting on.

"Even if it did happen, I'd just get up again, yanno? Like last time." Sans patted Papyrus's back again. "Cause you don't give up on me. You're the only one who knows how to drag me outta bed, heh. Come on, this isn't like you. Let's just get home so you can get some sleep, okay?"

Papyrus was silent for awhile, still holding Sans. He had stopped shaking.

"You're right. You are right, of course. This is not like me. The Great Papyrus doesn't let anything get him down."

"Yeah. That's…that's right, bro."

Maybe he'd said the wrong thing. But it wasn't like Papyrus was forcing himself to be happy, right? Happiness and positivity just came easily to him. So much easier than it came to Sans.

Papyrus let go of him and stood, then reached down to help Sans back to his feet. Sans took his hand and let Papyrus pull him all the way up. The fear and doubt and exhaustion was gone from Papyrus's face; he was smiling again. Sans put his own smile back on.

"That was quite the tumble, though. Very impressive! You almost face-planted!"

"Heh, right? I guess I'm pretty good at slapstick on top of puns, huh?"

"Ugh, maybe to someone with no standards at all." Papyrus dusted some snow off Sans's front. "Why don't I carry you the rest of the way? Just-to be on the safe side!"

"You know? I changed my mind. I think I'm down for that. Or I guess _up_ for that."

Papyrus ignored the pun and crouched again so he could lever Sans up onto his back. Then he stood.

"Nice. I do like feeling tall."

"Oof, well, enjoy it while you can! You're getting FAR too heavy for this!"

"I'm considering it back pay for carrying you around all the time when we were babybones."

"Keep that up and I'll drop you!"

Sans just laughed. He even made it sound genuine.

"I'm sorry I scared you, bro."

"Nyeh! The Great Papyrus was not scared! The Great Papyrus is not afraid of anything! I was merely surprised, that's all! Though I really shouldn't be surprised that you are more than willing to take a nap in the middle of a snowy street!"

"Heh. Still, I'm…sorry. I'm…"

He couldn't, though. Papyrus hated it when he did this, maybe because it sounded so much like self-pity, or maybe because Papyrus just hated the idea of Sans apologizing for Sans. For being a burden-literally, sometimes, like right now. For being such a terrible brother. For being so damn weak and so damn pathetic that even just slipping in the snow made Papyrus think he might be Falling Down. For being the reason for just about every bad thing in Papyrus's life, or at least every bad thing in Papyrus's childhood.

For coming out so very wrong.

And that was the worst thing, really, the thing Sans hated most about thinking about any of this, why he tried to bury it all even deeper than anything about timelines or nonexistent monsters. It was one thing to make a joke of what a mess he was, because if he could laugh about it, then none of it could possibly affect him. It was another to be faced with the concrete _fact_ that he was _wrong._ Monsters weren't supposed to be born with only one HP, and they certainly weren't supposed to then survive, and then keep surviving, and then live all the way to adulthood. Monsters like that weren't supposed to Fall Down and then get back up against all odds, not when so many others, monsters much worthier than Sans, were never afforded a second chance.

And parents were supposed to love their kids. Full stop.

"You…know the reason I don't talk about this stuff or…about them, I guess, it's-it's not cause I want to keep secrets from you. It's not like that. You do know that, right?"

Papyrus was quiet for a moment. Sans couldn't see his face from this angle, but he thought Papyrus might be startled. Sans was never the one to broach the topic.

"I-yes, I know that, Sans."

"Okay. Good." Sans sighed heavily, resting his forehead on Papyrus's clavicle. "I just…"

Papyrus waited, patient. For several long moments, the only sound was his booted feet in the snow.

"I could forgive them for giving up on me. You know? I mean…you don't remember. You were too little. It was- _I_ was exhausting for them. This sick kid who came out all wrong."

"Sans-"

"I know, I know. Hold on, just-let me finish. Just-heh. I'd get it, if it was just me. I'd get it."

A sick kid. A kid that slept all the time, that required constant attention, constant monitoring, a kid that had to be taken to all kinds of healers, all kinds of doctors, because there had to be an answer, right? There had to be a way to _fix him._ But there wasn't. And the days and years wore on, and he didn't get better, and his HP didn't improve, and he could never be left alone because what if he tripped or what if he bumped the edge of a table, and it was all so damn _exhausting._ Such a burden.

Such a disappointment.

He was spiraling. He clamped down on it, because he wasn't going to go to pieces, wasn't going to sink into the mire of self-hatred, not while Papyrus was right here with him.

"But they gave up on you, too."

Parents should love their kids. But they hadn't.

"They gave up on you, and…I can't forgive them for that."

One sick kid. And one kid that had too much energy, that was too hyperactive, too loud, too _much._

"But you forgive them. And that's good. Because, heh, you're a better person than me. So I just…that's why I don't like talking about any of it, yanno? I don't wanna be bitter about it around you. I don't want to bring you down more than I already do."

"You don't bring me down, Sans!"

"Heh."

"And-and I don't believe that they gave up on me, or on either of us!"

"Yeah." Sans closed his eyesockets. "I know you don't."

"They went on vacation, that's all!" Papyrus bobbed his head in a nod. "And…and something just prevented them from ever coming back!"

Sans didn't answer. He kept his eyesockets closed.

"Still, I understand what you are saying, brother." Papyrus's voice softened. "And…whatever kind of people they really were, well…it doesn't matter! Because-you didn't come out wrong, Sans! You came out as my brother! I wouldn't trade you for a thousand parents!"

Sans started laughing. It was real this time.

"Heh. What about a million?"

"Not even a BILLION!"

"Wow. That's a lot of parents compared to one lazy brother."

"But he is a VERY GREAT lazy brother! Even if he is GREATLY LAZY!"

"Aww, man. All this _mush_ is gonna make me _blush."_

"That wasn't even a joke, Sans, that was just a rhyme! UGH! I take it all back!"

Sans chuckled again. Papyrus laughed as well.

They were quiet the rest of the way home, but Sans was grinning the whole way. He put all of it out of mind, just for a little while. He had his brother. Everything was alright so long as he had his brother.

Papyrus was yawning openly by the time they reached home, and he was fast asleep the moment Sans finished _Goodnight Moon._ He was so tired he hadn't even stopped Sans to make him explain again what a moon was. Sans stayed with him after, listening to Papyrus breathe and "nyeh" quietly in his sleep. He could head down to his lab in the basement now, finish the last minute preparations on the scanner, probably before morning. Then it would be ready to go as soon as Sans got up the nerve to talk to Alphys.

Papyrus looked peaceful. All the strain and doubt and sadness gone in his sleep.

Tomorrow. He'd get started on it tomorrow.

Sans curled up next to his brother and went to sleep.

* * *

"Knock knock. Who's there? Boo. Boo who? Aw, no need to cry, it's just me. Heh."

It was a nice day. Unseasonably warm for Snowdin, not that anywhere in the Underground really had seasons. Sans was lounging against the Ruins door, killing time. He could just barely make out Doggo and Papyrus in the distance. Papyrus had tried to rope Sans into repairing the bridge, and when that had inevitably failed, Doggo had become his new target. Doggo didn't have that much willpower, and had been looking for an excuse to get out of the house anyway. It had been another week with no change from the Fallen monsters, so at this point everyone was looking for distractions. The two had to be about halfway done with the new bridge by now.

Sans rapped his knuckles against the door again, two times.

"Knock knock. Who's there? Dwayne. Dwayne who? Dwayne the bathtub, it's overflowing."

Sans had a notebook open against his knees, intermittently jotting notes about the timeline scanner in his basement. All of it was superficial. The machine itself was complete; all it needed now was Alphys's input and it would be fully functional. The problem now was that Sans was a coward, though he was pretty sure that even the average monster would have some trouble in this situation. How were you supposed to ask for help from someone who probably hated you? The last time they had spoken, Alphys had been blaming him for her father's death, which she'd had every right to do. She had no reason whatsoever to help him now.

Sans knocked again.

"Knock knock. Who's there? Dontsu. Dontsu who? Don't suppose you can give me advice on how to talk to a friend whose life I basically ruined…"

The door didn't answer. Sans sighed and snapped his notebook closed. He tapped his pen against the cover, thinking and watching the tiny figures of Papyrus and Doggo. Papyrus would certainly be better at this. Alphys and Papyrus would probably have gotten along great, if Sans had ever bothered to introduce them.

Sans raised his hand to knock on the door again but paused when he saw movement in the distance. A third figure had appeared at the bridge. Sans squinted. It looked like one of the other dogs. The three of them seemed to be talking amongst themselves.

This was probably bad news. Maybe someone had finally gone to dust. Sans figured he should probably get up and go see what was happening, but that would involve actually getting up. Sitting was infinitely more comfortable; plus, the longer he waited, the longer it would be before he had to learn the name of whoever had finally died.

He sighed and knocked on the door again.

"Knock knock. Who's there? Dustin. Dustin who? Dustin the wind." He grinned wryly. "That wasn't funny. Sorry."

A moment later, Sans's phone buzzed in his pocket. He pulled it out to see a text from Papyrus.

COME TO THE BRIDGE! THERE'S NEWS!

"Welp. Guess I gotta _shut the door_ on these jokes for now, eh?"

Sans got to his feet and teleported himself to the other side of the chasm, reappearing near his sentry station. From there, he simply walked to the bridge, pocketing his notebook as he went.

Dogamy was at the half-completed bridge, having a heated discussion with Doggo while Papyrus looked on, his eyesockets wide.

"I don't know," Dogamy was saying, shaking his head. "I've never heard of something like this before."

"BUT THIS IS GOOD! ISN'T IT?" Papyrus said, spreading his arms. "THE KING WOULDN'T MAKE SUCH A REQUEST UNLESS-SANS!"

Papyrus waved him over. Doggo and Dogamy both gave Sans strange looks.

"Hey, guys. 'Sup?"

"Ugh, how do you just appear like that! I hate that!"

"Did I miss you at your station?"

Sans shrugged and grinned. "I'm small enough that I'm pretty easy to miss. So what's going on?"

"THERE HAS BEEN A ROYAL DECREE!"

"More like a royal request," Dogamy said, rubbing at his chin and frowning in bewilderment. "King Asgore has requested that any monsters who have Fallen Down be sent to the Laboratory in Hotland."

Doggo folded his arms. "Apparently, the Royal Scientist is working on…on something that might actually- _cure_ Falling?"

"There might be a way to actually SAVE Doggerel, Best Dog, Doggo Sr. and Mrs. Drake!"

"Well…let's not get ahead of ourselves," Dogamy said, still rubbing at his chin. "All we know is that the Royal Scientist is doing some sort of experiment…"

"AND THAT THE KING IS SUPPORTING HER! That can only mean that King Asgore TRULY BELIEVES that it could work!"

"Experiment or not, if there's even the slightest chance to save Dad, I'm gonna take it. Even if it's unorthodox."

"Wait-wait, sorry." Sans held up both hands. "So let me…see if I've got this. The King wants people to just…send Fallen monsters to A-to the Royal Scientist. Because the Royal Scientist is conducting some sort of experiment with them?"

It didn't make any sense. Alphys was an engineer and a roboticist, not a monster biologist. More than that, even the most experienced healers and doctors didn't have the best understanding of monster physiology. Monsters were made up of magic and physical matter, but that physical matter varied greatly depending on the species. Something that affected one monster one way might affect another monster in a completely different way. It wasn't like monsters technically got sick, either. The only thing that always worked across the board was healing magic, and the degree to which it worked depended on both the caster and the subject.

But nothing worked on Falling. Healing magic simply had no effect. There was no such thing as a _cure_ for Falling; it was like saying there was a cure for death itself. When you Fell Down, you either got back up again on your own, or you didn't. That was all there was to it.

"That's basically it."

"Isn't it EXCITING? Everyone might finally get back up again!"

"I dunno." Sans looked between Dogamy and Doggo. "Doesn't it seem kinda…weird? Shouldn't someone ask just _what_ the experiment is?"

"Someone did already," Dogamy said. "Asgore says that it's 'classified.'"

Classified. Of course.

"How do we send them to the lab, anyway?" Doggo asked. "I'd want to send Dad as soon as I can, but moving him in his condition seems unsafe."

"The Royal Guard will be helping. The King is deploying us to different towns and villages to aid in transportation. We'll be moving everyone as safely as we possibly can."

This just didn't make any sense. What sort of experiment would possibly involve Fallen monsters? Sans wasn't any more an expert on monster physiology and monster souls than Alphys was. She had been working with _human_ souls last Sans had heard.

Just what was Alphys up to?

"Then, hell, what're we waiting for?" Doggo's tail gave a quick wag. "What about you? Are you gonna send Doggerel?"

Dogamy solemnly pressed a paw to the picture of Dogaressa's face emblazoned on his robe.

"He is Dogaressa's father, so I will be going along with whatever my sweet sugarplum desires."

Doggo laughed, his tail wagging harder. "Hah, I shoulda guessed! Well, come on, let's head back then. You bone boys should come back with us and help out. Well-probably not Sans."

"What?" Sans blinked, coming out of his thoughts. He put on a grin. "Oh. Yeah, you read my mind. I'll be no help at all."

"Truly, your laziness knows no bounds," Papyrus said, shaking his head. "BUT! THE GREAT PAPYRUS WILL ABSOLUTELY HELP IN ANY WAY HE CAN!"

"I guess I'll at least come back into town to watch the action. Wish Doggerel and everyone a safe trip and such. Heck, maybe I'll go to the lab with them, meet the famous Royal Scientist myself."

"Hey, yeah," Doggo said as he, Dogamy and Papyrus started to walk briskly back down the path toward town. "If she can really cure Falling Down, maybe she can also fix you!"

Sans kept his grin firmly in place. "…Heh. Well, there's no cure for laziness."

"I meant the-"

"ANYWAY! LET'S HURRY! Sans, we will meet you back in town!"

"Don't wait up."

The three of them took off. Sans made a show of following at his usual slow pace until they were out of sight.

Then he teleported to Hotand. It seemed he finally had a good excuse to talk to Alphys.

He landed near the entrance to the Laboratory, behind a small outcropping of rocks. There was already a bit of activity near the front door. As Sans stepped out from behind the rocks, he could see a handful of Royal Guards, as well as some monsters who looked like civilians. Two Royal Guards were wheeling a prone monster on a gurney into the lab.

Standing to the side of the door, tapping information into a tablet, was Alphys.

"Okay, e-end of the hall and um, leave him next to Biggs the Moldbygg. I can take them from there," she said, pointing with her tablet pen.

"Sure thing," a guard answered, and they disappeared into the lab with the Fallen monster. Sans watched as Alphys turned to the two Vegetoids and a Loox who were waiting nearby. Alphys smiled kindly at them.

"D-Don't you worry, I'll take very good care of them. I promise. There's nothing to worry about!"

"If they do Fall Down despite your best efforts…you will send us their dust, yes?" said one of the Vegetoids.

"I was gonna ask that too," said the Loox.

"Of course I will, of course." Alphys beamed. "Thank you so much for this, truly. I-I know how hard this must be, but this will be a huge, huge help, I swear."

Alphys looked up and finally spotted Sans. Her smile faltered. She looked back down at the other monsters.

"Anyway, I've got a lot of work to do. Thank you again."

The three monsters turned and moved away, speaking quietly to each other. Alphys pressed her tablet to her chest and looked through the lab door, checking on the Royal Guards inside. Sans stepped forward, hands in his pockets.

"Uh, hey there. I, uh…" Sans abruptly lost his thread. "Hi."

"Hi, Sans." Alphys glanced into the lab again, then looked back at Sans. She smiled thinly. "It's, um. It's been awhile."

"Yeah. Yeah, uh. Heh. It has." Sans rubbed the back of his skull, staring at his feet, trying to will himself to be a bit more courageous. This was about more than just his timeline scanner now. "So, uh…sorry to just show up out of the blue like this, but…"

He trailed off again as the two Royal Guards resurfaced from the Laboratory, now without the gurney. They stopped before Alphys.

"There anything else we can do for you?"

"No, no, um, I've got it from here. Thank you so much for your help."

"No problem."

"We're heading to Waterfall next, we've gotten word of two more to pick up."

"Oh, okay! Okay, excellent, I guess I'll…s-see you later? Thanks…"

The two guards left, and Sans and Alphys were alone again. Sans made a sound like he was clearing his nonexistent throat.

"So, uh, anyway…I wanted to-"

"Um-listen, Sans?" Alphys started fidgeting with her tablet pen. "I'd love to talk to you and-and, I know there's probably a lot to talk about, but I-I a-actually really am busy? I've got, um, there's a lot of work to be done, like a whole lot of work, so, I'm just…"

"No, yeah, I get that. I heard about this whole-this thing with Fallen monsters. That's part of the reason I'm-"

"Yeah! Yeah, so, so I really need to get started, and I just, I-I just really don't h-have time to talk right now, I'm sorry."

"Al, listen-"

"Alphys."

"…Alphys." Sans stuffed his hands back in his pockets. "Look, you-why Fallen monsters? What are you doing with them?"

Alphys's grip tightened on her tablet.

"My job. Which is-which is why I'd better go get started. I can't talk to you right now, Sans."

She started to walk into her lab. Sans took another step forward.

"Wait, please. That's not the whole reason I came. Just-hold on a sec? I know you probably don't want to see me and I know I don't have the right to ask y-"

"I have to go now, bye."

"Alphys-"

Alphys pressed a button on the wall and the door slammed shut in Sans's face. Sans stared at it for a moment, then sighed and pinched the bone above his nasal cavity. He'd screwed it up again. He raised his hand, hesitated a moment, then knocked twice on the door.

There was no answer.


	13. Rising

.

 **ENTROPY**

* * *

Chapter 13: Rising  


Warning: This chapter contains **body horror**

 _Are there dogs inside?_

* * *

All of the Fallen monsters were moved to the Hotland laboratory over the course of a few days. Things in town went back to normal fairly soon afterward. Where there had been a pall of grief and sorrow hanging over Snowdin like a cloud, now people were tentatively hopeful. Everyone seemed to be assuring themselves that good news was on the way. The change in atmosphere did nothing to alleviate Sans's doubts, but it was nice all the same.

Sans had tried calling Alphys once after seeing her at the Laboratory, but she hadn't even picked up-though he wasn't actually sure that it was anything personal. Other monsters had said much the same after other attempts to contact her. Mettaton mentioned on one of his programs that the Royal Scientist was working very hard and was not to be disturbed, and that if people _really_ wanted to call someone, they should call into one of his shows, anyway. King Asgore had also given a formal request to let the Royal Scientist work in peace. People had stopped clamoring for news after that, and things had settled back into the usual routine over the next week and a half.

Sans decided to just check out a few engineering books, both from the Snowdin Librarby and from the New Home Library, but the selection at both left a lot to be desired. He'd hoped to maybe just teach himself some basic engineering and finish his time scanner that way, but it was quickly apparent that the basics just weren't going to cut it. He could take a four-year program in engineering and still not have the knowledge or skills necessary. He needed Alphys. So once again, it was a matter of waiting. Eventually her experiments with Fallen monsters would end, and then maybe he'd finally be able to talk to her. If he assured her that he would never bother her again afterward, maybe she'd even agree to help him with only minimal coercing.

In the meantime, Sans usually found himself selling hotdogs, practicing knock-knock jokes at the Ruins door, or helping Papyrus set up the last of his revamped puzzles between the Ruins and Snowdin Town. The puzzles now included a completed electricity maze, several switch puzzles, and a high-tech randomized tile puzzle designed by Alphys herself. Sans's contributions amounted to exactly zero puzzles total, a point that Papyrus brought up at least twice a day.

Currently, Papyrus was showing Sans his very latest human trap.

"A plate of spaghetti?"

"NO ONE COULD POSSIBLY RESIST A PLATE OF FRESH SPAGHETTI! I even left a microwave so that the EVENTUAL HUMAN may heat it up once it is…SLIGHTLY LESS FRESH!"

Papyrus gave the microwave an affectionate pat. Sans decided not to point out that it wasn't plugged in, nor were there any outlets out here in the woods. Papyrus had already lugged the thing out here, as well as the table the plate and microwave were resting on.

"I think this spaghetti is frozen, bro."

"TRY TO PAY ATTENTION, SANS!" Papyrus stamped a foot. "THAT IS WHAT THE MICROWAVE IS FOR! NYEH! In any case, I plan to REPLACE the spaghetti portion of this trap DAILY!"

"Neat. Pretty good trap, then. This'll really _tangle_ anyone coming by."

"OF COURSE IT'S A GOOD TRAP! EVERYONE-UGH, SANS, THAT WAS BARELY EVEN A JOKE!"

"Heh."

Papyrus grumbled and folded his arms. "ANYWAY, no human NOR monster NOR animal, apparently, will be able to pass up an opportunity to try some of the GREAT PAPYRUS'S INCREDIBLE COOKING!"

"Animals too, huh."

Sans was about to make an animal magnetism joke, but Papyrus jerked a thumb toward a small rock formation.

"Mice, at least! There's a mouse that's been trying to get at my spaghetti all day!"

Sans looked where Papyrus was pointing. There was a tiny crevice in the rocks, exactly mouse-sized. As he looked there was a tiny squeak, almost as if the creature was listening.

"Huh. Didn't know there were any mice in Snowdin. Thought they were mostly in Waterfall and New Home. Isn't it too cold for mice?"

"MICE DO WHATEVER THEY WANT, SANS!" Somehow, Papyrus made this sound sage. "Who am I to judge such a CONNOISSEUR of good cooking?"

Sans took a few steps closer to the rocks and crouched down to see into the hole better. The occupant was standing boldly near the entrance, watching Sans with curious black eyes, like drops of oil. The mouse's fur was white-not exactly common among wild mice.

Out of nowhere, it occurred to Sans that it had now been almost ten years. Maybe ten years exactly, maybe a little more. It was impossible to pin down the actual time frame, and Sans had long since given up on trying. A decade. Ten years since Gaster had given him a simple task-recharge some random magic gauge that regulated the temperature in the mouse cages-and Sans had told him that he couldn't. Ten years or so since someone had told Sans that four test mice had escaped, and that in a fit of rage, Gaster had destroyed all the remaining mice. Ten years, give or take, since everything that had happened.

A decade of trying and failing to piece everything back together. And here was one of those pieces, staring up at him through too-intelligent, oildrop eyes.

"Aww, man." Sans's grin broadened as he met the mouse's gaze. "Would you look at that. Heh. You're one…determined little guy, huh."

"Are you talking to the mouse? CAN MICE TALK?"

"Nah." The mouse retreated further into its hole, out of sight. Sans stood back up and gave his brother a placid grin. "Heh."

"What's that look for?" Papyrus eyed Sans with suspicion.

"Nothin'. I just…remembered something funny."

Papyrus put his hands on his hips, seemingly annoyed. "Well, KEEP IT TO YOURSELF! We should move on! I want to show you my idea for the GAUNTLET OF DEADLY TERROR!"

"Sure, bro. Lead the way."

Papyrus marched onward deeper into the forest. Sans followed, casting a backwards glance at the mouse hole. For a moment, he thought he saw beady eyes watching him again.

He wondered if the other three had survived as well.

At the base of one of the many cliffs in the Snowdin forest, Papyrus had constructed a model out of snow. It was absurdly complex considering, but Papyrus had always had a bit of an artistic streak. The snow model depicted a long bridge, blocked with more hazards than was strictly necessary, including swinging axes and maces.

"Pretty impressive snow sculpture, bro."

"The real thing will be even MORE impressive!"

"Where you gonna get a bridge this long, though? Don't think there's any chasms that wide." Sans poked what appeared to be a small snow dog perched on the bridge, and the snow dog promptly crumbled. Papyrus made an annoyed sound.

"WELL, NO!" Papyrus shifted Sans out of the way so he could shape the snow dog again. "I'm planning on painting that big rock formation right outside the entrance to town! There, that's better. DON'T TOUCH IT THIS TIME, SANS!"

"Sorry."

"I'm going to start construction later today, and I need the model to be PERFECT! It's not PERFECT if it's in pieces, brother!"

"Okay." Sans raised a brow ridge at Papyrus. "I said I was sorry."

Papyrus sighed and put his hands on his hips, frowning at the snow, looking oddly distant for a moment.

"It's alright, Sans. That dog is ALWAYS annoying, even when he's a tiny pile of snow! ANYWAY! I want to show you the next trap I've constructed!"

"Is it far? I love seeing your puzzles, but my tibias are starting to ache. Ain't telling _fibulas."_

Papyrus groaned loudly. "Somehow, your puns are WORSE today than usual! It's not THAT far, Sans, don't be such a LAZYBONES! Even that MOUSE had more gumption than you!"

"Heh." Sans looked away, grinning faintly. "Well, not like that's hard."

It was a wonder the little guy was even still alive, actually. Mice didn't live more than a few years. Effects of Determination, maybe? They had given up on studying the substance before really learning all that much about it. The only real case study for the effects of Determination on a living thing was Gaster himself and, well. That was a pretty damn flawed case study.

Papyrus was saying something. Sans blinked and pulled himself out of his thoughts.

"What? Sorry, I was spacing out."

Papyrus glared at him, expression going from annoyed to outright frustrated.

"If you're going to be TOO LAZY TO EVEN PAY ATTENTION, then maybe you SHOULD just go home! You don't even HAVE any puzzles out here to calibrate, SO! WHAT'S THE POINT!"

"Hey…come on, bro don't be like that. I said sorry. I'm just kinda distracted today, that's all."

"Do you even CARE about my puzzles and human traps?"

"Of course I do. I always do."

"THEN! PAY ATTENTION, AND LET ME SHOW YOU THE LAST ONE, AND STOP COMPLAINING! It's not that far, so KEEP UP!"

Papyrus started walking at a brisk pace. Sans stared at his retreating back for a moment before trotting to catch up.

"Alright, alright, no more complaining. Jeez. You're in a mood today."

"THAT SOUNDS A LOT LIKE COMPLAINING!"

"No, it's commentary." Sans was already starting to lag behind as Papyrus kept up his pace. "Paps, is everything okay?"

"It's FINE, Sans! You're just being MORE ANNOYING than usual!"

Sans grumbled under his breath. "Okay, whatever. Shutting up."

The two of them lapsed into irritable silence. Papyrus got into moods like this from time to time, and usually there was something that set it off. Usually that something was Sans. Sans had known pretty much since childhood that the best course of action was to just apologize and stay quiet until whatever it was blew over.

Technically, that was his default reaction to most things.

Papyrus led him deeper into the forest, heading in the direction of the bridge and the Ruins door. Sans fell further and further behind, as Papyrus didn't seem to want to slow down for him. That was fine. Papyrus didn't need Sans right on his heels; Papyrus could probably use a bit of a break from him right now.

Eventually, they reached the bridge over the chasm. Sans noticed the trap immediately. It was less a trap per se, and more the fact that the bridge was now fixed. The wood was pristine and raw, and the whole thing looked quite sturdy.

"Oh, hey. You finished it."

"YES! With Doggo's help, it went quite smoothly! As smooth as a WOOD FINISH! NYEH HEH HEH!"

Sans grinned at joke, but decided not to comment on it. Mostly because he wasn't sure he'd be able to resist making one of his own, and jokes seemed to be a point of contention right now.

"It looks real good, bro. Bridge like that will last a hundred years."

"THANK YOU, SANS!"

Sans stepped closer to examine it better, studying the odd addition to the bridge. Papyrus had built what looked like vertical bars across the bridge, but they were spaced far enough apart that Sans wasn't sure what their purpose was. Maybe a stylistic flair? They looked like they'd make actually crossing the bridge unnecessarily precarious.

"So what're the bars for?"

"TO STOP HUMANS, OF COURSE! THE GREAT PAPYRUS HAS COME UP WITH A VERY CUNNING TRAP. If the humans are coming from the Ruins, then! THEY MUST CROSS THIS BRIDGE! But where they expect to find a bridge, they instead find-A FENCE! No human will be able to get through!"

Sans chuckled a bit and Papyrus narrowed his eyesockets at him.

"NOW what is funny?"

"Heh, the bars are too wide, bro. A human could just slip right through. They're not all that big."

Papyrus stared at him, and Sans realized he had made a mistake. Sans stuffed his hands in his pockets and waited for it.

"I THOUGHT! YOU WERE DONE COMPLAINING, SANS!"

"Sorry, Paps." Sans grinned sheepishly. "It's not really complaining, just-"

Papyrus stamped a foot. "I WORKED VERY HARD ON THIS TRAP, BROTHER! AND ALL YOU CAN DO IS CRITICIZE IT!"

"Heh, it's more like _construction_ criticism…"

"SANS!" Papyrus yelled so loud his voice echoed off the cliff face nearby. "ENOUGH! WITH THE PUNS! I AM TIRED OF THEM!"

"Okay." Sans stared at the snow between them. "Okay, sorry."

"YOU NEVER TAKE MY TRAPS SERIOUSLY! YOU NEVER TAKE _ANYTHING_ SERIOUSLY!"

"Hey, come on. Ease up, bro."

"I AM NOT STUPID, SANS!"

Sans looked up at him again, frowning. "I never said you were. I've never thought-"

"EVEN IF THE BARS ARE TOO WIDE, IT'S NOT ABOUT STOPPING A HUMAN! IT'S-IT'S ABOUT SLOWING ONE DOWN, SO THAT I MAY CAPTURE IT! THERE IS NO POINT TO A HUMAN TRAP IF IT DOES NOT HELP YOU CAPTURE THE HUMAN!"

"Okay. I got-"

"NOT THAT YOU WOULD UNDERSTAND! YOU HAVE NEVER LAID A SINGLE TRAP OUT HERE OR DESIGNED A SINGLE PUZZLE!"

Sans decided to just shut up and wait for Papyrus to finish. He probably deserved this. Shouldn't have said anything about the traps and puzzles at all.

"YOU ARE SO LAZY! YOU NEVER WORK HARD AT ANYTHING! ALL YOU DO IS SLEEP AND SLACK OFF, AND YET SOMEHOW EVERYONE LIKES YOU! EVEN THOUGH YOU DON'T TRY TO MAKE FRIENDS, BECAUSE YOU DON'T TRY AT ANYTHING. BUT ALL I DO IS TRY! AND YOU'RE MAKING FUN OF ME FOR IT!"

Sans kept his hands in his pockets and his gaze on the snow. He hadn't really _meant_ to laugh. It had just seemed…amusing. Like making the bars too wide was a simple, silly mistake.

Papyrus threw up his arms. "WHY DID YOU COME OUT HERE AT ALL IF YOU WERE JUST GOING TO MAKE FUN OF ME? WHY DID I EXPECT YOU TO TAKE SOMETHING SERIOUSLY FOR ONCE?"

"Okay." Sans raised his voice just enough to be heard. He started walking, moving past Papyrus and heading back the way they'd come. "I'm, uh. I'm gonna let you cool off a bit. I'll be at Grillby's. Sorry I upset you."

"OF COURSE YOU'RE GOING TO GRILLBY'S! I WOULDN'T BE SURPRISED IF YOU WERE ON THE PARTY-PLANNING COMMITTEE!"

Sans kept walking. "No idea what you're talking about."

"THE PARTY THIS WEEKEND!" Papyrus yelled after him. "THE COSTUME PARTY YOU WEREN'T GOING TO TELL ME ABOUT!"

Sans stopped and sighed heavily, shoulders sagging. He turned back to his brother, rubbing the spot between his eyesockets.

"Papyrus, I don't…have _any_ idea what you're talking about. What _party?_ I didn't hear anything about a party."

It didn't seem like the best time for anyone to throw a party. But then again, maybe that was the whole point. Monsters were like that. When bad things happened, they tended to throw themselves into something happy and positive, a sort of aggressive attempt to cheer themselves up. It made sense. Sinking into despair was dangerous for a monster.

Papyrus didn't answer right away, and after a moment Sans looked up at him. Papyrus looked like he wasn't sure whether to be suspicious or surprised. He had his arms folded across his chest and his eyesockets were rather wide.

"YOU MEAN YOU…really don't know about it?"

This was exhausting. "No one told me about any party, bro. I pretty much just woke up, and then I was-slacking off on some stuff, and then I came out here with you."

Sans saw Papyrus grip on his arms tighten. He frowned down at the snow for a moment before looking back up at Sans.

"I thought-I suppose I thought you'd heard. It's going to be QUITE BIG, I think most of the town will be there…"

"Is that why you've been in a bad mood all day?" Sans stared off into the woods. "You thought there was some secret party I wasn't telling you about?"

"You-keep A LOT of secrets, brother! I thought this was one of them!"

Sans didn't answer. No wonder, then. No wonder Papyrus was upset. It was probably just one more thing on the pile. One more disappointing thing his useless older brother had done. And then Sans had gone and teased him over his traps. It was a wonder Papyrus didn't lose his cool more often.

A wonder he put up with him at all.

"I am-Sans, I am SO sorry."

Sans sighed again and closed his eyesockets.

"You don't gotta apologize, bro."

"YES I DO! I should not have jumped to conclusions! I should not have yelled. I was just…frustrated. I…I suppose I am just…I thought perhaps you knew that I had not been invited, and were trying to spare my feelings."

"I get it." It was something Sans would probably do, after all. Wasn't that the whole reason he kept most of his secrets from Papyrus?

He gave a vague shrug. "But it sounds like I haven't been invited either, so. Although that's…kinda weird. If it's big enough to include most of the town, why exclude us?"

The townsfolk weren't even remotely that petty, and it wasn't like Sans or Papyrus had done anything terrible to deserve being shunned. Frowning, Sans pulled his phone out of his pocket so he could check his messages. He was terrible about checking them regularly, and there was at least a dozen he hadn't read.

"Especially the Great Papyrus," Sans said, scrolling through his phone. "Everyone loves that guy."

"If that's true, then why…?"

Sans looked up when he heard the shake in Papyrus's voice. Papyrus was hugging himself now, staring down at the snow and looking forlorn.

"Why aren't I more popular, Sans? Why don't people like me?"

"What? Paps, _everyone_ likes you."

"But I don't have any _friends."_

Sans stared at him.

"You-Papyrus, that's just not true. What about the dogs? What about Undyne?"

"Undyne is the Captain of the Guard! She does not have TIME to be friends with someone who isn't even a guard! She certainly does not think of me that way! I am just her student!"

Sans was _positive_ that that wasn't true. Not with the way he'd heard Undyne talk about Papyrus.

"And the other sentries? Our neighbors? The dogs?"

"They all just…put up with me! I am not close friends with any of them! Doggo…Doggo was the one who told me about the party, but he did not invite me!"

"Jeez, that's…that doesn't sound like him. He's kind of an idiot, but he's not that dense. Usually. Maybe…" Sans scrolled through his phone some more, casting around for some reason why Doggo would bring up a town-wide party directly to Papyrus's face, and then fail to invite him.

Seemed like the mutt needed a talking to.

"Maybe he just knows you don't like Grillby's? You said it's at Grillby's, right? And you're not a fan of that kind of frivolity. Maybe he figured you wouldn't want to go."

"That is EXACTLY what HE said!" Papyrus squeezed his eyesockets closed briefly. "He said he would invite me, but that he knew I wouldn't like it! And I probably wouldn't! I DESPISE Grillby's! And I don't like how rough the dogs' parties can be! But I still want to be INVITED, Sans! I just-want to be INCLUDED! I want to know that people WANT ME AROUND!"

Sans was quiet for a bit, eyelights dimming. This wasn't anything new; it wasn't coming from nowhere. This had to be the sort of thing that had been building up for a long time, that was only now starting to come out. How long had this been going on? How long had Papyrus felt so…so lonely, so left out?

And how the hell had Sans never even _noticed?_

At that moment, Sans found a message in his phone that he had missed: _Costume party at Grillby's - Saturday!_

So there it was. Sans pocketed his phone.

"Well…" Sans spoke slowly, trying to choose his words with caution. He didn't want Papyrus to think Sans was pitying him. Papyrus had never _once_ pitied Sans, even though there were plenty of times in Sans's life where he would have deserved it.

"It looks like-like there's just been a whole lotta miscommunication here. I, uh, seems Grillby sent me a message about the party earlier and I ignored it. So…I'm invited. Which means, yanno, that I can-extend the invitation to you."

Sans chanced a glance up at Papyrus to see how he was taking this. Papyrus's face was unreadable.

"I mean, if. You want to, that is. Cause, even if no one else does-and I really think they do, Paps, even if you can't really see it-well, yanno. _I_ always want you around."

There was a silence, and then Papyrus sighed. It was less exasperated and forlorn than before.

"You are my brother, Sans. You are SUPPOSED to! I just…want FRIENDS! I know I'll have LOTS OF FRIENDS once I get into the Royal Guard, but! I want friends BEFORE that!"

Sans wondered if this was his fault. He had clung to Papyrus like a leech his entire life, taking up most of his time, and probably also most of his energy. Papyrus must not have felt like he could just go out and make friends if he had to look after his needy, clingy older brother the whole time. No wonder Sans had never noticed how bad it had gotten. He was selfish. He _was_ the problem.

And he didn't know how to fix it. This was the best he could do.

"Do…do you want to go to the party, bro? It's a costume party. I have an idea for something that'll _really_ stand out. You'd, heh. You'd have to beat potential friends off with a stick. It'll be at Grillby's and it'll be loud and hectic, but…you could use it as a chance to talk to people. Take a break from all the puzzles and sentry stuff and-maybe make some friends, right? If you want. No pressure, bro. And it's not-it's not just some kinda pity invite. I legit have a really good idea for a costume that'll be as cool as the guy wearing it. I just, uh. Want you to be happy, yanno?"

Papyrus was quiet for an uncharacteristically long amount of time. It was still hard to read his face. He was still hugging himself, still staring at the snow. Sans held his breath and waited, desperately hoping that he was doing this right.

After what felt like an eternity, Papyrus let go of his arms and spoke.

"What…kind of costume did you have in mind?"

Relief flooded Sans's marrow and he gave a tentative grin.

"Something cool, bro. I'm thinking…famous, unbeatable hero. Intergalactic warrior who travels the cosmos and saves whole worlds. Something like that. With like, armor. And a cape. Even cooler than the Royal Guards."

Papyrus smiled just a little.

"That…SOUNDS LIKE THE PERFECT COSTUME FOR THE GREAT PAPYRUS!"

"I got the rest of the day off if you, uh, wanna go get started on making it. I saw some pretty good stuff at the dump the other day we could use for materials. We could make it a project. Still a few days till the weekend, and if we're gonna make it really cool, it might take awhile."

"THIS IS A GREAT IDEA, SANS!" Papyrus was smiling in earnest now. "You REALLY want to help me make it?"

"Sure, bro." Sans spread his arms. "It'll be fun."

"That is-VERY NICE OF YOU, BROTHER! Then let's go home and get started right away!"

He started marching back toward Snowdin, and Sans fell into step beside him. This time Papyrus's pace was slow, so that Sans could keep up. Sans kept grinning as they walked. Thank god they'd managed to salvage this. He hated it when they argued; it made his soul feel pinched and painful.

"Sans, I…really am sorry. That I shouted and that I said those things."

"Aww. It's okay, Paps." He reached up and patted Papyrus's arm. "I'm sorry I teased you about your traps. They're all real good."

"Well…" Papyrus rubbed his chin. "You MIGHT have been right about the bars being too wide on the bridge."

"It's still a good bridge. You know, I… _wood_ have hated it if I kept having to take a shortcut back and forth." Sans nudged Papyrus with his elbow. "Eh?"

"UGH, Sans!" Papyrus was hiding an obvious smile. "Terrible as usual!"

Sans laughed, feeling himself relax.

* * *

It was a pleasant afternoon in Snowdin Forest. Sans was supposed to be manning his station, but he had let himself take an extended break. No one ever really came out this far to make sure the sentries were doing their jobs, after all. And with his position now right in front of the Ruins door, it wasn't like he would miss it if a human did come by.

The spot was just too perfect. It had quickly become Sans's favorite area in the whole woods. Private, quiet and out of the way, like his favorite spot in Waterfall-the tiny little side cave with nothing but a bench and a single Echo Flower. He could nap, or practice magic and knock-knock jokes without any fear of being disturbed. And it was less boring than sitting at his station for his entire shift. Far be it from him to ever take a job a hundred percent seriously.

He reached up and rapped on the door twice, stretching as he pulled himself out of a nap.

"Knock knock. Who's there? Beats. Beats who? Beats me."

Things had been pretty hectic in town as people got ready for the party. It was nice to see Snowdin coming back to life. The party seemed to be a sort of combination of the town cheering itself back up, and sending good vibes to the Fallen monsters at the Royal Scientist's lab. Everyone was still very unclear as to what was even happening, but the idea that their loved ones might one day return to them had filled people with hope. Even if it was false hope, it was…nice to see everyone happy again.

He reached up and knocked again.

"Knock knock. Who's there? Cows go. Cows go who? Nah, cows go moo, buddy. Heh."

Meanwhile, Papyrus's costume was coming along real nicely. They were planning on finishing it tonight, with plenty of time left before the party tomorrow night just in case. The thing was mostly done already, and Papyrus was more excited than Sans had seen him in years. They'd decided to forego the cape idea in favor of Papyrus's favorite red scarf. It was easier for the smaller piece of fabric to flap dramatically in the wind, after all.

Sans knocked again.

"Knock knock. Who's there? Owls go. Owls go who? See, now you're gettin' it."

Sans raised his free hand and summoned some bone bullets. They sprang up from the ground in rows, very close together, the array wide enough that it spread across the entire path. Sans had gotten an idea from Papyrus's bridge with its too-wide bars. A fence-or a cage-was a pretty good way to trap someone, after all. It was the kind of attack that couldn't be dodged or avoided at all. If the anomaly that Gaster kept warning him about was so dangerous, maybe Sans would need something like that. Not that he expected to have to _fight_ anything. Gaster had made it sound like it was maybe a person or something, but how could a person be an anomaly? It was more likely that Gaster was referring to some kind of glitch or hiccup in the flow of time.

Whatever it was, it would be coming from the door. Sans was no closer to figuring out what the anomaly was, or talking to Alphys, or finishing the timeline scanner, but that didn't mean he could just sit back on his coccyx. Not entirely, at least. He had to be ready for anything.

Wasn't he always?

He let the array of bones vanish, then reached up and knocked twice.

"Knock knock."

"Who is there?"

Sans bolted upright, so startled he reflexively teleported about five feet away from the door. He stumbled backward, then promptly fell over on his butt. He stared up at the door, eyesockets wide.

Someone had answered.

But that was impossible. That was simply impossible. No one _lived_ in the Ruins, at least not as far as anyone knew. Maybe the occasional monster burrowed its way in, but it couldn't possibly be that common. Sans must have just been hearing things.

He squinted at the door, holding his breath and waiting to see if something happened.

"Who is there?"

The voice came again, louder this time. It was a woman's voice, formal-sounding, her tone practically demanding an answer. Sans looked around, as if maybe the voice could be coming from somewhere other than beyond the door. Like maybe someone was playing a prank on him.

But it was true. Someone was living in the Ruins. He had knocked, and someone had answered.

Sans picked himself up and walked back to the door. He should ask her who she was, or maybe explain himself, maybe just apologize for bothering her. Or maybe he should just not answer at all.

Instead, he replied with,

"Dishes."

There was a pause.

"Dishes… _who?"_ She sounded confused. Even for a monster, "Dishes" was a pretty unusual name.

"Dishes…" Sans grinned sheepishly. This was probably one of the stupider things he had ever done. "…a very bad joke."

There was another pause, longer this time. Sans was sweating. She would probably start yelling at him any second.

Instead, she burst out laughing.

It was loud, raucous laughter, the kind that would have her entire body shaking. Absolutely joyous, unapologetically gleeful. She sounded like she hadn't heard something so hilarious in years.

It was one of the best laughs he'd ever heard in his life. No one had ever laughed like that at one of his jokes, especially not one that terrible.

Sans sat down again in front of the door, chuckling despite himself. Her laughter was utterly infectious.

As her howls of mirth began to peter out, Sans knocked again.

"Uh, knock knock."

"Oh goodness!" She sounded like just talking was difficult. "Who is there?"

"Spell."

"Spell who?"

"W-H-O."

"Pfffthahaha!"

He listened to her break down again, dissolving into fits. God, did she always laugh so earnestly? He had to find out.

"Knock knock."

"Oh dear, another one! Who is there?"

"Nobel."

"Nobel who?"

"No bell, I knock."

She went off again. It was positively delightful. She must _really_ like bad jokes. That was perhaps somewhat _anomalous_ behavior, but would some kind of existential threat laugh like that? Sans didn't think so.

He rattled off a few more, trying to come up with his very best. None of them were particularly good, but that didn't seem to matter. She laughed at every single one, and she laughed _hard._ It was incredible. Even when he was doing stand-up at the MTT Resort, no one ever laughed this hard. Occasionally a joke would land really well, but it was usually a one in a dozen shot.

After a few minutes, she begged him to let her catch her breath, so he did so. He listened to her come down slowly, still giggling. She sounded like she had taken a seat against the door.

Then, in yet another unexpected move, she knocked twice.

"Knock knock."

Oh man, he was in for it now. His grin widened even further.

"Who's there?"

"Old lady."

She was keeping her composure very well. It seemed that even her delivery was top-notch.

"Old lady who?"

"Oh! I did not know you could yodel!"

"Oh my god." Sans pressed a hand to his face, laughing. It was as terrible as all the ones he'd told, and that just made it _funnier._ She was very, very good at this.

"Man-man, I gotta admit, stranger, I don't think I've ever met a real bad joke enthusiast other than myself till now."

"I have always loved jokes! And sadly, I so rarely find myself with the opportunity to tell any!" She chuckled brightly. "This has been a delight! I have not laughed so hard in ages!"

"Well jeez, good thing I showed up when I did. Glad I could _delight_ up your day some."

"Oho! That was a good one! How…ah, _enlightening_ to hear you have more than just knock knock jokes. You must be quite the comedian!"

"Heh, well, I do have a comedy routine over at the MTT Resort. I do okay. I'm not much for the _limelight,_ though."

"I have not heard of this 'MTT Resort.' I have lived here in the Ruins for a very long time now, you see. I am afraid that I am, hee hee, somewhat in the _dark_ about more recent developments in the Underground!"

"Yeah?" That was interesting. Mettaton had built his big fancy resort hotel right next to the Core awhile ago-probably over a year now. She did sound a bit older than Sans, and she had an old-fashioned way of speaking. She might have been in the Ruins for years and years, all alone except for the missing branches of the spider clans and the occasional ghost..

Sans scooted closer to the door.

"Well, it's this big hotel over in Hotland, run by Mettaton. You heard of Mettaton? He's the _bright star_ of the Underground."

Everyone and their mother had heard of Mettaton. If she hadn't, then she truly was living in total isolation.

"No, I am afraid that the name is not familiar. I have not… _met a ton_ of people over these last few years!"

That one was just downright clever. Sans couldn't hold back another bout of laughter.

"Heh, wow, you really are good at this."

"Ah, I have thought of another one! Knock knock."

"Who's there?"

"To."

"To who?"

"No, that is incorrect! It should always be 'to whom!'"

Incredible.

Sans lost complete track of time. He and the lady on the other side of the door chatted for hours, mostly telling jokes and trading puns. She was remarkably easy to talk to, and he ended up telling her a few things about the state of things in the Underground, as well as a few things about himself. She in turn chatted about the Ruins-apparently there were vast networks of puzzles inside, probably an ancient holdover from the war, when monsters were still uncertain about whether humans would follow them underground or not. All these puzzles needed to be maintained, and the lady was the self-appointed caretaker of the Ruins. Mostly, she said, this just meant keeping things clean and running.

She also wasn't quite as alone as Sans had thought, which was both heartening and rather fascinating. Apparently there was a small loose-knit community of monsters within, mostly loner-types like Migosps and Looxes. It was as Sans had guessed-most of them had simply burrowed or flown into the Ruins one day and had just decided to stick around. The lady didn't interact with any of them very often, except to make sure they were staying out of trouble. She said she had a feeling that they found her intimidating.

Eventually it was evening, and Sans remembered that he had agreed to help Papyrus try and finish his costume that night. He had also completely missed the end of his sentry shift, but that was fine. Clearly no one had even noticed. For all that it was one of the more important sentry positions in the Underground, no one really cared about it all that much.

"My apologies," the lady said. "I had no idea it had gotten so late."

"Nah, I lost track of time too," he said, getting to his feet. "But it was worth it. Not every day I meet someone who likes bad jokes as much as I do."

"Nor I! For obvious reasons, I suppose."

"But yeah, I gotta get back home. Hoping to finish Papyrus's costume tonight."

"Ah, for the costume party you mentioned! It sounds like it will be quite the soiree. Is Papyrus a friend of yours?"

"He's my brother," Sans said, grin widening. "Basically the coolest guy in the whole Underground. He's really looking forward to the party. Mostly for the chance to show up looking like a super cool warrior."

"He sounds lovely! Well, I hope you and he have fun! Thank you for telling me so many wonderful jokes today. It really did brighten things up in here."

"Heh, glad I could _shine some light_ into your life." Sans hesitated, tapping his thumbs together. "Hey, you know, I come out here all the time. Mostly just to hang-nice and quiet and all. You think, uh, maybe we could chat again? I know _way_ more jokes."

The lady on the other side paused for a moment.

"That…you know, that would be quite lovely! I was actually going to ask you just about the same thing, but I feared that perhaps you were merely passing through. It would-indeed be very nice to speak to you again."

Sans practically beamed.

"Awesome. Well, uh, I'll try to come by tomorrow before the party. But if not then, then probably the day after. I work as a sentry right nearby."

"How convenient! Then, I hope to speak to you again soon."

"Heh. Right back at ya. Talk to you soon."

With that, Sans left and headed back to close up his station. There was something of a spring in his step. Who'd have thought that someone so interesting lived in the Ruins, of all places? It had been a very, very long time since he could say that he had actually made a friend. He'd almost forgotten the feeling.

It was a nice feeling.

There was a practical benefit to this whole thing as well. If she lived in the Ruins, and apparently knew it like the back of her hand-or paw or hoof or what have you-then she might be able to see the anomaly coming long before Sans did. She might be able to warn him, give him a bit of a headstart. He wasn't sure how to broach the topic of anomalies, or timelines, or cryptic warnings from existentially-challenged former bosses, but at least it was an option.

Though it occurred to him that they hadn't even exchanged names. He'd been so caught up in the joking that he'd completely forgotten to ask. Maybe that was for the best. She must like her privacy if she had locked herself away in the Ruins. Plus it kept a certain air of mystery to things.

More important than all that was the fact that Sans had made a brand new pun friend. He couldn't wait to see the look on Papyrus's face when he told him.

* * *

It was the biggest party Snowdin had seen in years. Most of the town showed up, even if only for an hour or two, as well as some monsters from the rest of the Underground. There was also the usual array of party crashers. The whole thing began inside Grillby's, but as more people showed up it spilled out into the streets. Undyne and a few of the guards arrived, both to participate and to try and keep the peace. The latter turned out to be not necessary-Snowdin had a reputation for rowdiness, but that usually just meant a few drunk dog monsters wrestling in a snowbank.

The fact that it was a costume party instead of a random excuse to get drunk helped. There were enough kids there that even the real party animals kept themselves in check. Most people were in costume, and the mood was jovial.

Sans and Papyrus showed up early, since Papyrus didn't believe in being fashionably late. Papyrus was practically vibrating the whole way to Grillby's, equal parts nervous and excited.

"You do not think we could have improved my costume at all?" Papyrus had asked. "MAYBE WITH GLITTER! Or a sword!"

"No way, bro. You're gonna be the coolest guy at the party."

Papyrus's costume was perfect as far as Sans was concerned. He looked truly epic when a breeze caught his long scarf. Papyrus had always cut a pretty dramatic figure, but between the stylish boots, the chestplate and the scarf, he looked like a seasoned warrior ready to risk life and limb to save the day. He looked like a _hero._

It helped also that, by contrast, Sans had of course gone for the laziest costume possible. He'd simply gotten a plain T-shirt and written "2,000 lbs" on it in marker. A skele-ton. Papyrus hated it, of course.

As soon as they walked into Grillby's, Sans knew he'd had a good idea for once. Everyone who even saw Papyrus complimented him on his costume. Total strangers started chatting with him, and it wasn't long before Papyrus settled into his usual role as a social butterfly, striking heroic poses the whole time. This should get him some of that popularity he so craved, if not a few new friends. Sans let him be, since at this point Papyrus didn't need him around to potentially draw away attention. He slipped away and took his usual post at the bar so that he could people-watch.

It was a good party. Snowdin had finally gotten its happiness back. It had been a long two weeks.

Sans, always content to hang back and not get involved, stayed at the bar for most of it, chatting to anyone who bothered to come by and say hello. This was mostly the Grillby regulars. Punky had plenty of sarcastic commentary about all the visitors to town, particularly anyone from the city. He was one of a handful of people not wearing a costume, saying it was "too establishment." Dizzy came by to flirt, share a few drinks and eventually fall asleep in one of the booths, like usual. She was even worse than Sans was about that, which was saying something.

Midway through the night, Sans was able to track down Doggo and corner him.

"Next time you're telling my brother about a party?" Sans said, voice level. "Make sure you actually invite him too."

Doggo squinted at him. "Jeez, sorry. I figured there wouldn't be a point. I know he doesn't like these sort of things, plus he hates Grillby's."

"Fair. But telling someone about a party and then not inviting them is pretty dang rude. Yanno?"

Doggo rolled his eyes. "Fine, fine, I got it. You're always looking out for him, but you realize I do _like_ the guy, right? Everyone likes Papyrus. It wasn't anything personal-but whatever. I'll apologize to him."

"Thank you. I appreciate it."

"You know, you act like you need to defend him, but if he's really going to be a Royal Guard someday, his big brother rushing to his aid will be the _last_ thing he needs. You're sheltering him too much."

"Heh." Sans turned and walked away, back to his place at the bar. "Tell me something I don't know."

Sans went back to drinking slowly and watching the party. It was nice. Everyone was happy, having fun. Despite the noise, Sans felt rather at peace.

Grillby also appeared during one of his breaks, looking exhausted.

"Hey, buddy. You're looking burnt out."

Grillby gave a soft hiss, like a sigh, and leaned on the counter.

"Should have hired more temp help." Grillby's voice was soft, barely audible above the din.

"Well hey, having all the food buffet-style was a good idea," Sans said, grinning widely. "At least no one's broken any windows yet?"

"Yet."

"Great party, though. Just what we needed around here. Everyone's happy."

Grillby was silent for a little while, idly wiping out a glass.

"You seem happy as well."

Sans glanced at him. "Pfft, 'course I am. I'm always happy. Always smilin', right?"

Grillby didn't have much in the way of facial features, but Sans got the sense that if he had eyebrows, he would be raising one right now.

"Not always happily."

Sans looked back toward the party, not sure how to answer. Grillby had always been ridiculously perceptive, but Sans had thought he'd been doing pretty okay for himself. Usually the endless jokes were enough for people not to look too closely.

"Yeah, well." Sans shrugged. "I'm happy right now, at least."

There was some kind of spatiotemporal anomaly coming, and he still needed to get Alphys's help, but-his brother was having a grand time at this party, no humans had shown up for over a year, and Sans had met someone with a sense of humor like his own. He'd even managed to go out and chat with her a bit before the party. At least in this exact moment, things weren't so bad.

"I am glad," Grillby said with a nod.

At that moment, Doggo climbed up on one of the tables and started barking loudly. Sans snickered to himself as Grillby made an annoyed series of crackling sounds, pushing himself off the counter.

"Had to happen eventually," he hissed.

"Everyone! Everyone, listen up!" Doggo said in between barks as more and more people turned toward the noise.

Then Dogamy climbed up on the table beside him and began barking for attention as well.

"Please, everyone! We have an announcement to make!"

"Listen up!"

Grillby was already starting to make his way across the bar toward them.

"Just a moment, Grillby, this is important!"

Doggo held up his cellphone and waved it. Sans could tell that both of them were drunk, but this sounded like more than just drunken shenanigans.

"I just got a call from the Royal Scientist!"

"Dogaressa received one as well!"

That shut up the room almost entirely. Even Grillby stopped, folding his arms and waiting for the two dogs to get to the point. Sans watched from his stool.

"Dr. Alphys says that the monsters who had Fallen Down have all gotten back up!"

"She saved them!" Doggo barked. "All of them are alright!"

"They will be returning home to us sometime tomorrow."

"They're all coming home!"

The entire restaurant exploded into noise as people started cheering or asking questions or proposing toasts. All of the dogs started barking with excitement. On the opposite side of the room, Undyne scooped Greater Dog up into a crushing hug. Grillby trudged back toward the bar to get everyone a fresh round of drinks.

Sans watched the whole thing, tapping his finger against the side of his empty glass.

"Huh."

She'd cured them. Alphys had somehow cured all the Fallen monsters. It seemed like the perfect end to a great day, but…

If nothing else, it _was_ the perfect opportunity. Alphys had to be ecstatic after such a success, which meant she might be amenable to talking to Sans. So he slid off his stool, made his way to a more shadowed corner of the bar, and teleported.

He landed in Hotland, right in front of the Laboratory door. The transition from loud noise to total silence was a little jarring. Sans stepped closer to the door and knocked.

He waited a minute, but there was no answer. Sans knocked again.

No answer.

That was kind of odd. It was late, but not so late that Alphys would be asleep already. She tended to stay up until the wee hours, anyway. Plus she had to expect that maybe people would want to come by to congratulate her, or even come try to collect their family members early.

Sans pressed the intercom button on the side of the door.

"Al-uh, Dr. Alphys? It's, uh, Sans. You in there?"

He stepped back to wait and see if she answered. When she didn't, he pressed the buzzer again.

"I heard about the Fallen monsters. It's pretty freaking amazing. I know you're probably really busy, and I know no one's supposed to bother you, but uh…"

The longer he stood here, the more awkward he felt, all the excitement and contentment of the party fading. He still had no idea what to say to her. And she must be really happy right now, knowing she'd saved so many lives. Wasn't his presence just going to ruin that?

But…there was still that _but._ Something about this felt oddly familiar. Fallen monsters got up on their own sometimes, but the reasons for it were always inexplicable. If Alphys had discovered some way to bring people back from Falling, it would be the most important scientific accomplishment in probably a century. A manual, scientific cure for Falling.

Why did that seem familiar?

He pressed the button again.

"Dr. Alphys, are you there? Listen, I-I don't want to interrupt or put a damper on things, but I-I still need to talk to you sometime. So if you're there, could we maybe just…think of a time in a day or two for us to talk?"

He was going about this all wrong. Maybe he was too tipsy to be thinking straight. This was probably coming off as pretty stalker-ish behavior. Even if she was inside, she might just be ignoring him.

He _wished_ he could just leave her alone. That would be so much better for her.

Sans sighed and pushed the button a final time.

"Alright, well. Congrats on saving those people."

With that, he took a few steps back and teleported, landing outside his and Papyrus's house. It was an unceremonious way to end the night, but Sans didn't feel like going back into the noise of Grillby's. He was tired. It felt like there was a weight on his mind.

* * *

The monsters that Alphys had cured did not return the next day.

Everything progressed as usual. Several monsters from the community took it upon themselves to help clean up Grillby's and the adjacent streets. Papyrus spent an hour or so in the morning regaling Sans with stories of people he had met at the party, saying that he was certain several of them would be his friend now. Visitors from other regions of the Underground checked out of the Snowed Inn and departed one by one, and Snowdin returned to its usual quiet self. The Guard Dogs went on their patrols, Sans worked a shift in Waterfall and another shift at his sentry station/hotdog stand in Hotland. Papyrus refused to change out of his costume and went on patrols still wearing it, then left for an evening training session with Undyne. Sans went to Grillby's as soon as work was over, like usual. The dogs were sitting at their usual table, all looking various shades of confused.

The Fallen monsters hadn't come back, and there was no word from the Royal Scientist as to why. Or any word from her at all. Sans heard Dogamy assuring the others that she probably just needed to keep them an extra day for observation. To make sure they were truly stabilized.

But the monsters didn't return the next day, either. Nor the day after that.

When three days had gone by, word started getting around that Dr. Alphys was not returning calls, texts, or emails. When four days had gone by, people started knocking on her door, but no one ever answered. At five days, people started asking Mettaton, who just shrugged and encouraged people to tune into his newest show.

A week went by. The Fallen monsters still had not returned, and Alphys had seemingly vanished from the face of the Underground. It was then that people began to ask King Asgore directly.

The King informed the families that Dr. Alphys was certainly still alive, as she had answered at least one of his calls, but that was the extent of his knowledge. All she had told him was that she "wasn't ready yet," so Asgore encouraged patience.

Most people found the whole thing suspicious, and Sans was no different. He stopped by the lab one more time himself, but if she wasn't going to answer for concerned family members, she certainly wasn't going to answer for him. Normally he would have been content to just wait and see what happened, but the odd weight in his mind, the odd sense that he had forgotten something, made it impossible not to think about.

He took to spending more time in his own lab, rereading all of his notes from the past several years, tinkering with the machine and the scanner. He hadn't kept things very well organized, so he decided to sort things out, try to arrange his notes and research chronologically. He pored over the data dumps that he and Alphys had managed to get from the time machine's damaged CPUs. He'd been over all of it before, but none of it had ever seemed all that pertinent. Most of it was nonsensical, probably from the machine attempting to to run scans as it passed through the void, and the rest of it was either error messages or structural information from the machine's degradation. Everything else had been lost.

Looking over and rereading everything helped refresh his memory, bringing a few things that had gone fuzzy over the last few years back into focus. He found himself studying the machine's nonsense data again. Represented visually, it was all long, unique strings of numbers, some with very little internal repetition, others with none at all. The actual amount of strings seemed to be gargantuan, but the machine had only retained twelve, as well as a portion of a thirteenth. After exactly 31,121 digits, each string ended in exactly twenty zeroes. Sans had always found that strange. 31,121 was a pretty specific number, and it couldn't be a coincidence that each string of numbers degraded into zeroes after that many digits. The zeroes themselves seemed significant as well, but given that the whole thing was just a bunch of numbers out of any sort of context, Sans couldn't for the life of him understand it. Nor did he know any mathematicians.

He toyed with the numbers idly for a few days, either in the lab or while bored at his sentry stations. He tried converting some parts of the strings into binary or hexadecimal or base-11, but it didn't produce anything all that interesting. He also took a closer look at the areas of repetition within some of the strings, and also compared instances where a digit was the same number between multiple strings. All of it seemed to be entirely random. Sans couldn't get his head around it, and trying was giving him a headache.

Maybe he could plug all the numbers into the scanner once it was complete. But that of course implied that it would ever be complete, and with Alphys all but missing, that was currently up in the air.

Fortunately, he had Papyrus and the lady through the door to distract him. Papyrus had not taken his costume off since the party, and had taken to calling it his "battle body." The lady through the door had started discussing baking in between rounds of jokes. She was an avid baker, mostly of pies.

"Man, sure hope I get to try a slice someday," Sans had said one day after she described her particular method for apple pie.

"Oh! Maybe…maybe someday."

It was clear by now that she had no intention of opening the door anytime soon. She referred to her stay in the Ruins as a sort of self-imposed exile. When Sans had asked why, her tone had gone soft and she'd said only that it was because of a disagreement with someone she had once known. That was all she said on the matter, and Sans didn't press.

"In the meantime, perhaps I can give you one of my pie recipes!"

Baking and cooking in general were things Sans had never had much interesting in, partially because cooking had sort of become Papyrus's thing over the last few years. He wasn't exactly keen on learning an entirely new skill, but it would be nice to have something in common with his door friend other than just a love of jokes. Plus it was a distraction from numbers, anomalies, and Alphys.

Still, the number strings stuck with him, and he was never sure why. They had never really stood out to him before, but these days it was like there was some kind of pattern he was missing. He was a monster like any other, for the most part, so the idea of a pattern he couldn't understand was like an itch he couldn't scratch.

One night, almost two weeks after Alphys had cut off all contact with the outside world, Gaster came to him.

It was remarkably ordinary dream, probably one of the most unadorned dreams Gaster had ever created. Sans sat in a black void, absolutely nothing around him. The floor, or ground, seemed to be made out of black glass. When Sans looked, he saw faint white characters crawling beneath the surface. Not Wingdings, which was Gaster's usual prerogative. There were myriad white circles with diagonal slashes through them, or a pair of curly brackets-braces-with nothing in between them. The symbols darted and skittered beneath the glass like fish in a pond.

"Huh. This one's new. It's barely even nightmarish, Doc."

"STOP. LISTEN."

Gaster's nonexistent voice was sharp enough that Sans looked up. There was of course nothing to see.

He hadn't actually _seen_ Gaster in…well, technically he had never seen him at all.

"Okay. Listening."

"NOT MUCH TIME. YOU WILL WAKE UP SOON."

"Well, you've got my attention while-"

"EMPTY SETS."

Each symbol beneath the glass flashed brightly, all in unison.

"Set theory." Sans propped his chin on a hand, watching the symbols. "Well, I guess from that perspective, the void counts as an empty set."

"YES." Gaster's sounded urgent. "EXACTLY."

"So how does this relate to the anomaly?"

"YOUR ZEROES." Sans felt a brief pressure on the top of his skull, as if someone had gently tapped him. "THINK, SANS."

"My-?"

Sans woke up.

It was much earlier than he usually got up. Papyrus, of course, had already awakened and gone out for a morning shift. Sans had several hours before he needed to be anywhere, so he got some leftover coffee from the kitchen and went right down to his lab. He went back to the number strings again, bringing them up on his computer and scrolling right until he found all the zeroes.

Twenty zeroes at the end of each string. 31,121 digits, then twenty zeroes.

Sans set aside the fact that there were specifically twenty for the moment. The significance lay in the zeroes themselves. The series of zeroes was the only thing that every string had in common. It wasn't too much of a leap to assume that every possible string-and that was something like 31,121 to the power of 10-must also end in zeroes.

Zeroes had pretty obvious connotations. It meant that whatever information the time machine had been scanning came to an abrupt end after a given number. That information could be just about anything, and the number itself could represent anything from distance to time. The point was that it _ended._ The zeroes were something coming to an end.

And Gaster had been pretty specific for once. Mathematical symbols for empty sets-a set with nothing at all in it. A void. Sans highlighted the zeroes in one of the strings and changed it to an empty set symbol: a circle with a diagonal line through it.

All of these strings of numbers ended in a void.

Sans got to his feet, pulled on his coat, and teleported to Hotland.

He landed right out front of the Laboratory. He checked to make sure no one was around, then walked up to the front door and knocked. There was no answer, but he hadn't really expected one.

Sans pressed the buzzer.

"Al? Dr. Alphys. It's me. I need to talk to you. It's really important-I think I found something."

He stepped away from the door, actually pacing back and forth a few feet, feeling more agitated than he had in ages.

Alphys didn't answer. Frustrated, Sans hit the buzzer again.

"Dr. Alphys, I don't know what's going on in there, but I don't really care. I know you don't want to talk to me, but this is-something's wrong. Something's _fundamentally_ wrong, and I need-I need your help."

No answer. Sans stepped back, scrubbing at his face. He didn't know what to do. Something was starting to take shape in his mind-a theory, a horrible one. He'd been laboring under the assumption that the anomaly Gaster kept warning him about, over and over, was simply some kind of hiccup in the timestream. Maybe some kind of…temporal fracture or something, and Sans had figured that the worst case scenario was another divergence, like had happened when Gaster was erased. The effects something like that could have were far-reaching and nigh-unknowable, but not necessarily deadly.

This was different. Something-several somethings-were _ending._ There was no way of knowing _what_ was ending without the timeline scanner. It could be as benign as literal, physical roads that came to dead ends, or it could be as dire as lives.

Sans had a very bad feeling that it wasn't something benign.

He knocked again, louder and more desperate this time, but of course there was no answer. She wasn't going to answer. Alphys was the _only_ one who could do this. Sans had briefly considered tracking down another engineer, but Alphys was the only one who had ever worked with pre-divergence technology. Any other engineer would be hard-pressed to even understand some of the mechanical theories involved. Alphys had always said that the circuitry alone was completely baffling.

He stared at the door. All bets were off now. If she wasn't going to come to him, then he would just have to go to her. It was a messed up thing to do, but he was running out of time and options.

Sans took a breath, glanced around to double-check that no one was nearby, then teleported into the lab.

He landed just inside the door. This was the first time he had ever been inside since Alphys had taken over as Royal Scientist. The entire building had been renovated, and everything was completely unrecognizable. It seemed most of the interior walls had been knocked down in favor of one large laboratory space, with some doors leading to what Sans assumed were closets and side rooms, and apparently a bathroom. There was now an escalator leading up to the second floor, and that seemed to be where Alphys's living quarters were. The main laboratory area was dominated by an enormous split-screen TV monitor, with what looked like several dozen video feeds of different areas of the Underground. It looked like Alphys had set up cameras just about everywhere. Other than the screen, there were a few workbenches and some basic laboratory machinery.

The whole place was a bit of a mess, moreso than Sans had expected. He'd been to her apartment plenty of times-while Alphys wasn't exactly tidy, the lab looked more like Sans had been running things. He wondered if that was a recent development or not.

The lab was devoid of life, and silent but for the hum of fluorescent lights.

"Dr. Alphys?"

Sans's voice echoed through the lab. He waited near the door for a moment, but there was no answer. He wondered if he'd been wrong. Maybe she wasn't here at all; maybe she'd holed up somewhere completely different.

"Alphys?" He tried again. "Sorry, I kinda let myself in."

Still no answer. If she was here, he had a feeling she would have come out by now to confront him. Unless she was _really_ upset-then she might just keep hiding.

Sans found himself hesitating again. He hated going about things this way. This was invasive, just walking into her lab like this, practically tracking her down. He had never been good at sticking to any sort of personal morals, but Alphys had been a friend once. He didn't belong here.

But what choice did he have?

He began searching the lab, checking the video screen to see if there was anything telling there, opening a few closets, peering up the escalator. Barging into her actual living space was where he drew the line, at least for now. If he couldn't find her today, he could come back tomorrow. He called her name a few more times, but there was still no answer. Nothing on any of the workbenches seemed to indicate what she had been working on. Most of it seemed to be related to Mettaton, if anything.

Sans hovered near the escalator, tapping his chin and frowning. She wasn't here, at least not in the main lab, and he had a feeling he would have heard something by now if she was upstairs. She could be in the basement, but that was assuming it even still existed. They might have just filled the whole thing in during the renovations. There was now a bathroom where the old elevator would have been.

Though that in and of itself was kind of strange. Sans didn't know the first thing about architecture, but positioning a bathroom over an elevator shaft seemed like it would affect the plumbing.

Sans went and knocked on the door, just in case. There was no answer of course, but the door was cracked open already, so Sans pushed it open the rest of the way.

It wasn't a bathroom. It was an elevator.

"Okay. That's…weird."

Why disguise an elevator as a bathroom? Maybe she was using the basement as her real lab? Considering how little there was in the way of actual laboratory equipment here on the ground floor, it made sense. Sans knew the basement had maintained more of it's original, pre-divergence structure, so she would have way more space down there.

And if the elevator was disguised, it meant that probably no one even knew it existed. Alphys had always said that her work was extremely classified, so that made sense too.

She might be down there right now. Sans sighed, mentally braced himself, then walked to the back of the elevator and hit the button.

It was kind of funny, he thought as he rode it downwards. The last time he had actually used this elevator, he and Gaster had been bringing the time machine to the Core.

The elevator dinged, and Sans stepped out into a hallway. It was even quieter down here, the lights much dimmer. He could tell right away that there hadn't been as many renovations down here. He couldn't really remember the old lab or its layout, but everything was very familiar. Even the floor tiles were the same. The hall was long, with no doors at all; it was completely empty except for a few screens on the wall.

"Alphys?" Sans called. "You down here?"

He headed down the hall, feeling more and more apprehensive with every step. It was oppressively quiet in here. Sans checked one of the screens, but they all seemed to be switched off. He kept going until he finally reached a large room with branching corridors. There wasn't much here either, except for a very large door with four locking mechanisms, some more video screens, and a vending machine.

Sans walked up to the door to try opening it, but all four locks were engaged. With no way of knowing where it went, Sans couldn't risk teleporting to the other side. He knocked instead, and the sound echoed down the hallways, much louder than Sans had anticipated. He cast a nervous glance down the halls as the echoes faded.

"…Alphys?"

Where was she? And if this was where she had been conducting most of her research, where were all the Fallen monsters? The lab seemed completely deserted-as deserted as the last time he'd been here.

"Man…" Sans said, running a hand over the top of his head. He'd started to sweat a little. "This is-"

A sound came from deeper in lab, a grumbling, groaning noise that Sans felt in his ribcage. Sans froze.

That hadn't sounded like machinery.

Sans looked around, watching for any sign of movement. It was impossible to tell where the sound had even come from-it was like it came from everywhere. Sans waited, perfectly still and silent, listening hard.

After a minute or so, there was another sound from further away-a discordant rasp, almost like a squawk.

"Okay."

Sans took a step back toward the hall with the elevator.

"Ooookay, then."

 _Something_ was down here, and Sans didn't think it was friendly. Maybe it was time to leave and try again tomorrow. Just go home, try to settle his nerves, try to work the numbers some more. It was probably cowardly, but Sans had never had a problem with that sort of thing.

He turned, and found the way to the elevator completely blocked off. For a moment, Sans thought some kind of door had closed behind him without his knowledge. But the thing blocking the hallway didn't look entirely solid. It was pure white, and _oozing,_ some of it dribbling onto the floor.

"Shit."

A gaping black hole appeared in the center of the white mass, and the hole made a _sound._ It was like several animals growling in unison, pitched so low it made the floor tremble.

Sans stepped backward, and the thing disengaged from the wall and ceiling with a wet sound. As he watched, the mass twisted and shaped itself, the ooze forming into something like a body.

It looked like a monster, but it was like no monster Sans had ever seen or even heard of. It was enormous, maybe even bigger than a Boss Monster, twice as tall as Sans and maybe twelve feet long. As it finished shaping itself, six limbs formed along with a long, whipping tail. The black hole rose up from the thing's center, forming a sort of head around itself, topped with two pointed ears. The hole pulsated in time with its breathing, dripping black fluid.

The thing leaned toward Sans and made another one of those thunderous growls.

"Shit." Sans reeled backward until he was pressed up against the wall. "Holy shit."

The head lowered, and the creature took a menacing step toward him. Sans raised both hands, palms out.

"Hey. Hey, hey, easy, easy there, I-I don't mean any harm."

The ear-like appendages twitched and its head canted to the side, advancing again. It seemed like it was debating whether to charge or not. It growled again, and the whole surface of its body rippled like disturbed water.

"Can you understand me? Stop. S-Stop."

Shapes flickered in the black spaces between its limbs, like snarling faces. Sans's soul was hammering in his ribcage. He tried to press backward, but there was nowhere to go. He had to get out of here, he had to leave. This thing was going to attack any second, maybe even eat him.

It moved forward again.

"Wait. Wait, stay back. I-I don't want to hurt you, but-"

It snarled, gurgling and spilling black froth from the hole in its head. Sans inhaled sharply and summoned an array of bones above his hands.

"Stay _back."_

The thing seemed to hesitate. Its ears pricked, and its head canted back the other way. The hole pulsated a little faster and seemed to track the bone bullets as they moved. A different sound came from within it, almost like a dog giving an inquiring growl.

Sans frowned, glancing between the floating bones and the creature.

"What, you…you like these?"

He moved the bones a bit to the side, and the thing's head followed; Sans moved them the other way, and it gave another inquiring rumble. Its tail started to thrash erratically back and forth. Almost like it was wagging.

Even with terror gripping him, Sans thought he had an idea. He let all of the bones wink out except for one, then raised that one higher into the air.

The creature sat back on its haunches, or at least the impression of haunches, and looked up expectantly at the floating bone. Its tail thrashed faster, splattering white ooze onto the walls.

Sans stared at it, eyesockets wide.

"You're…you're kinda like a-?"

 _"No, stop!"_

A shrill voice echoed from down one of the halls, and Sans was so startled that the bone vanished-right as the creature surged upward to try and catch it. The creature made a low keening sound as it lost its prize, and Sans teleported a few feet to the side. The creature crashed back to the floor right where he'd been standing. Sans backed away, summoning another array of bones.

"Stop!"

Sans looked over to see Alphys charging toward them from down the hall.

"Al-?"

"Endogeny, _stop,_ stay! Stay! Sans, d-don't hurt them!"

The creature gave a warbling, roaring sound, stumbling back and forth on its six limbs, whole form vibrating. Its head whipped back and forth, as if searching for the missing bone. Sans moved backward and Alphys drew level with him, almost pushing him out of the way as she positioned herself between Sans and the creature. She looked terrified and exhausted, and her labcoat was filthy.

"Endogeny, stay! Stay, calm down! Sit! L-Look, look what I've got…" Alphys shakily produced a box of dog treats from under her arm, dug into the box and held one up to the creature. The thing gave a sort of prance and moved toward her, lowering its body, tail wagging.

"Good, that's good. N-Now sit, okay? Sit."

It sat back on three of its limbs. Alphys sighed in relief, and tossed the dog treat into the black hole. Sans couldn't see where it went, but the thing-Alphys had called it Endogeny-gave a happy-sounding whine and lay down, tail thumping against the floor.

"Good. Good dogs." Alphys stepped forward and patted its head. "God. Oh my god…I th-think my soul's going to explode…"

Sans tried to speak and his voice came out rather high-pitched.

"A-Alphys, what-"

She whirled on him, the terror back in her face.

"Sans, what the hell a-are you doing here?!" She turned away from Endogeny. "How did you g-get _in_ here?!"

"I…I came looking for you, I needed… I found the elevator…"

"You can't be in here! _You can't!"_

"Wh-"

"D-Did anyone come with you? Oh god, did anyone else come down here?!"

Sans quickly shook his head. "No, no, it's just me."

Alphys dragged her hands down her face. "Oh, thank god, thank-S-Sans, you can't b-be here, y-y-you need to leave!"

"No, what-Alphys, what is all this, what-" Sans gestured at Endogeny, now vibrating peacefully on the floor. "What _is_ that thing?"

"They're Endogeny, and th-they're not-they're not a thing, I can't explain it, Sans, y-you need to just leave, j-just leave and, and d-don't tell anyone what you saw, you never sh-should have come here! Why did you come here?!"

"I'm-Al, no, I can't leave. I need to talk to you, I didn't-I didn't want to break in, I just needed-" He stared past her at Endogeny, starting to shake.

He was starting to remember. Something was clicking into place. Fallen monsters getting back up, strange oozing dog creatures…

"W-We can talk later, I can't-"

"Alphys, what _are_ they?" He couldn't stop staring at them, at the black void that made up their face. "What-what did you-?"

It couldn't be. It just _couldn't_ be. It wasn't possible.

"Sans, _later,_ I-I need to-"

"Are they-are they one of the Snowdin dogs?" Sans turned to stare at Alphys, his eyelights disappearing. "Doggerel? Doggo Sr.?"

One of Endogeny's ears twitched, but other than that, they didn't react. Alphys wrung her hands, digging her claws into the spaces between scales.

"Not-they're not _one_ of them…" She was looking everywhere but at Sans.

"Alphys, what _the hell happened?"_

"I-I discovered this substance," she said haltingly, and before she could even get all the words out Sans was stumbling back against a wall. He clapped a hand over his mouth. He felt dizzy, like he was going to start retching.

"Oh god…"

"I-I didn't know it would go so wrong-"

 _"Oh my god."_

"I w-was just-I was just trying to-"

All at once, Sans remembered something Gaster had told him in a dream, one of the worst dreams, one he had tried so hard to forget, years ago now:

 _SHE WILL MAKE ALL THE SAME MISTAKES._

Sans, for maybe the fifth time in his whole life, took off running.

"Sans!"

He ran down the rightward hallway, the direction Alphys had come from. He passed through a large room lined with hospital beds and saw something white and misshapen slough away into a vent before he could see it clearly. Sans kept running, turning down another hallway.

Even though the layout had changed, even though the basement laboratory had been renovated, he knew exactly where it was. There was one place it could be, only one area large enough.

And only one way Alphys could have gotten hold of a substance that had changed one of the Snowdin dogs so horribly.

Sans reached the largest room in the lab and skidded to a stop. There it was, looming from the ceiling, as enormous as he remembered. Alphys must have modified the design, but he recognized it instantly. Skull-shaped, with mandibles that curved down like pincers, two gaping holes like eyesockets, massive tubes curling away from the main structure into the ceiling and walls.

 _And it's shaped like a skull,_ he'd said, eons ago. _I love it._

The Determination Extractor.

Alphys had built a Determination Extractor.

Sans fell to his knees. He stared up at it, breathing fast, shaking so hard his bones had started to rattle.

He barely even heard Alphys come scampering into the room.

"Sans? Oh god, Sans." She crossed the room to him, and he felt her grab his shoulder. "We have to go, please. Th-There's more of them down here, th-they get confused easily, you might, y-you might get hurt, please, you need to…Sans?"

"You didn't." Sans tore his gaze away from the Extractor and stared up at Alphys instead. "God, Al, tell me you didn't."

"I-how-?"

"Tell me you didn't. Tell me you-I don't _understand."_ Sans clutched at the sides of his skull, thoughts scattering. "Everything was erased, I-I thought I'd gotten hold of everything that hadn't been, how-how did you-how could you have _built it?"_

"Built…?" Alphys jerked away from him, eyes widening in horror. She looked up at the DTE. "You mean-you mean you've-?"

Alphys started to scream, but slapped both hands over her mouth midway, cutting off the sound.

"No!" She dragged her hands away from her face, tears starting to leak from her eyes. "That was why the blueprints felt s-s-so strange, _that_ was why- _no, how could I h-have b-been so s-s-stupid?!"_

She staggered, then crumpled to the floor near Sans, curling her tail around herself protectively.

"You found…you found blueprints?"

"It was during th-the r-renovations!" she wailed. "O-One of the workers found it under, under some rubble and as-assumed they were mine! It d-didn't even occur to me to question it, I just…I just _took_ them, a-and when I looked at them later I, I _knew_ something was wrong, but I didn't-I c-couldn't figure out what, and th-the design seemed w-workable, a-and I'd already been developing th-theories about, about a _substance_ within the human souls, a-and the more I looked at the blueprints th-the more I realize they were e-e-exactly what I needed, and I didn't-I didn't _question it!"_

"But why not? _Why not?_ You knew about the old Royal Scientist, you knew-"

 _"Because I'm not like you, Sans!"_ Alphys yelled, cutting Sans off. "I can't-I can't retain things like you can! I c-can't even remember his name anymore! This stuff, it just-i-it gets away from you, it goes all, all fogged over, and I couldn't…"

She trailed off and buried her face in her hands. Sans watched her, gripping the front of his hoodie with one hand.

"I should have known. I…"

Alphys sobbed into her hands. Sans looked away and stared at a point on the floor.

For awhile, they were both silent.

"You injected monsters with Determination."

"How-do you even know that word?"

"Because we studied it before." His eyesockets closed partway, and he lifted his head to look up at the DTE again. "This isn't my first time seeing that thing."

There was silence again but for Alphys's quiet sniffling. Sans stared at the floor, trying to collect himself. Trying to think. Trying to stop his soul from shaking its way out of his ribs.

"Al…"

She uncovered her face long enough to look at him. He met her eyes.

"We need to talk."


End file.
